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Topic: Fuel Pressure

in Forum: C3 Fuel, Emission Control, and Exhaust Systems

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Fuel Pressure (1/21)
6/26/10 2:23am

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

My 82 crossfire is getting closer to running correctly I think anyway. A few weeks ago before I went to Japan I orders a fuel gauge system for my car. I installed it today and it reads 5 pound. That would explain why that when I jump on it feels like it wants to die for lack of fuel.

Does it also have anything to do with ruff idle?

I changed the fuel filter and it was really dirty. I guess I need to pull the fuel pump and fuel gauge system out of the fuel tank. Does any one have suggestions on what to look out for and what to replace or hints on how to do it other than what is in the Shop Manual (I have one of those).

Also I have heard that I should adjust the fuel pressure to somewhere between 12 and 14 pounds. I was also told that 82 fuel pumps may not put out that much pressure and I should replace it with a 85 fuel pump.

Does anyone have any objections to doing that?

I have not read about getting access to the fuel pressure adjustment on the crossfire so I do not know what I should ask about that but will start reading up on it tomorrow. I just wanted to give you guys a chance to provide some feed back before I start working tomorrow.

Thanks in advance
Gil

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Fuel Pressure (2/21)
6/26/10 7:33am

crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094

First suggestion is to pull the fuel pump and replace it with a new pump either 82 or 85. The short rubber fuel hose to the pump that is inside the tank is notorious fo deteriorating. The pump comes out the top after removing the fuel door and associated hardware around the door. It will come out, it just takes the appropriate amount of twisting and turning accompanied by a little blue language to get it out. When the pump finally starts out, make a note of which way everything was pointing so you wont have to go through the experimenting process again. You can replace it with an 82 pump that will put out about 11 pounds of pressure or with an 85 pump which will put out much more. If you do put in an 85 pump you will have to modify your drivers side throttle body so that you can adjust the pressure regulator to notice any difference. If you arent comfortable with modifying the throttle bodies then install the 82 pump as the 85 pump will make absolutely no difference. If you do install the 85 pump you dont want to go much over 14 psi on the pressure or you will blow the diaphram in the throttle body. If you are only getting 5 psi at the throttle bodies then YES that will cause idle problems as well as acceleration problems. The factory settings are for 9-11 pounds at the throttle body but my car runs better with the 85 pump and a setting of 14 psi. If you decide to install the 85 pump I can give you directions on how to modify the throttle body so you can adjust the factory sealed fuel pressure regulator which includes removnig the anti-tamper plate in the regulator. You will also need a tool, either bought from Dynamic Crossfire Solutions or home built so that you can get to the regulator screw one the plate is removed, it cannot be done with standard tools. I build my own from a flexible carburator adjustment tool from pep boys and a piece of copper tubing....just call me bubba. You may also want to balance the throttle bodies to make sure they are in sync. This involves drilling out an access hole in the TBs and knocking out more anti tamper plugs and breaking a factory weld on the TB linkage. A water manometer is needed to do the balance but one can be bubba built for less than $10 which works well. I am on the road at present and dont have the links to the balancing procedures but can provide them the first of the week if you are interested. What fuel pressure gauge did you install? DCS?

Fuel Pressure (3/21)
6/26/10 7:56am

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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2552

I WOULD REPLACE THE FUEL PUMP THEN SEE HOW IT RUNS. YOU MAY NOT HAVE TO MESS WITH THE PRESSURE REGULATOR AT ALL. IF THE REGULATOR IS WORKING CORRECTLY LEAVE IT ALONE. THAT'S WHAT I DID AND IT WORKED JUST FINE, I PUT IN THE '85 PUMP, GIVES YOU MORE VOLUME AT HIGH SPEED THEN THE '82, BUT I'VE HEARD A NEW '82 PUMP WORKS FINE ALSO. BALANCING THE TB'S IS A GOOD IDEA.

DAVE

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Fuel Pressure (4/21)
6/26/10 2:10pm

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

I purchased the gauge setup from DCS along with the tool. Did not know what the end had to look like so I spent the money. Now that I know what it looks like I think I could build one but I'm home so little with my travel that time is always an issue.

Question if I put in a 85 fuel pump do I need to do anything with the fuel regulator prior to starting it up the first time. Or will the regulator setting be such that it will not blow anything?

Also I know that I can order a fuel pump from one of the many Corvette suppliers but I would like to pick one up locally at O'rielly, Carquest, Autozone or Napa will all or any of these work just fine. Or does someone have a recommendation which one to stay away from.

Fuel Pressure (5/21)
6/26/10 3:08pm

crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094

You wont "have" to do anything to the regulator if you put in the 85 pump but you wont be getting any more pressure to the TBs than the factory setting which will probably be good. The pressure from the 85 pump wont blow anything. I installed a Delco fuel pump from the local GM dealer in mine because wrestling that thing out of there wasnt something I wanted to do a second time. Anything you do to get that pressure up from 5psi and the accompanying increase in volume will make a world of difference. If in the future you decide to mod the pressure regulator you will need a rebuild kit for the TBs on hand.Crossfire19822010-06-26 12:10:06

Fuel Pressure (6/21)
6/26/10 3:25pm

crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094

In case you decide later to do the FP regulator mod, here are some pretty detailed instructions that I put together a while back. I make no claim to be a crossfire guru but have modified two this way with great results. Lots of this information is from reading the crossfire injection vault forum and from posts from the guys there. If you arent a member there already, I strongly suggest you join and look at what they have.

Making the fuel pressure adjustable is not rocket science or really difficult, it just takes a little time and patience to do. You will need to order a throttle body rebuild kit before you start because you will be disassembling parts with gaskets between them. The kit is available from Ecklers as well as other suppliers. Once the gaskets are disturbed, you will need to clean the surfaces and install new gaskets and "O" rings. Pay careful attention to how everything goes together so you will know how to reassemble. Taking pictures as you go is a wise idea.

First off, you will NOT need to remove the throttle body bases from the intake. You will need to remove the injector "pods" or "towers" from the bases. This can easily be done with the bases on the car. You will need to remove the 5 screws that hold the top of the tower to the tower itself. Once the 5 screws are out, you may need to tap the top the cover with a screwdriver or small hammer to jar it loose from the tower. After it is loose, remove the top and attached fuel fuel pressure regulator. Removing the injector itself is easy, just use a screwdriver to pry it out, here you see me using ahandle of a pair of pliers as a fulcrum for the lever. Pay PARTICULAR attention to the "O" rings and metal ring. These MUST be installed exactly right when you disassemble. Getting the injector back into its place with the spacer and "O" rings will be a difficult chore. It MAY be possible to leave the injector in place but scraping off the old gasket will be difficult but there are "O" rings and a screen filter on the injector itself that you will probably want to replace. You will next need to remove the the fuel pressure reguator from the lid. This will be done by removing the 4 screws that hold it in place. There is a STRONG spring in the regulator that mut be contained as you unscrew the 4 screws. This can be done either by mechanical clamps or with your hand . The spring is strong but not to the point that you cant hold it. Release all the parts that are inside and day attention to how the parts are arranged. When taking the screw mechanism out of the regulator try not to rotate the screw as this will either increase or decrease the regulated pressure, you will do this later when it is all reassembled and you can watch the pressure gauge. You dont want to inintentionally adjust it up too high and start blowing gaskets and diaphrams. There is a "plug" in the bottom of the regulator that blocks the adjustment of the fuel pressure. This plug must be removed by using a punch to drive it off, it will not give much resistance. Once the plug is removed, the regulator can be reassembled just as it was before. With the plug removed, you will be able to get to the adjustment stud. You now should be able to see how the tool works. By turning the stud, it moves the washer inside of the regulator and increases or decreases the spring tension inside of the regulator. Once the tower is reassembled onto the base and the injector is reinstalled, the tool is used to reach under the throttle body, engage the stud and adjust the pressure. The pressure you are looking for is 14 - 14.5.

Crossfire19822010-06-26 12:40:35

Fuel Pressure (7/21)
6/26/10 6:07pm

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

I am a member of the CrossFire Injection Forum. I took that recommendation a while back when it was given. I guess it is this forum that I seem to go first.

Thanks for the information. I just got back from purchasing an 85 fuel pump and about to start taking the old one out of the car. So sometime tonight or tomorrow after church I will have a chance to see where the fuel pressure will be with the new pump. hopefully it will be up to at least the 11 psi the GM manual says is the required pressure. I guess if I'm lucky enough to get that close we should see an improvement in drivability and I can then decide when and if I want to rebuild the FP regulator.

Do you recommend just adjusting the regulator and not rebuilding it. I have seen a couple of article on how to remove the plate to get access. Seem like rebuilding is not a requirement.

Fuel Pressure (8/21)
6/26/10 6:30pm

crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094

I think you are on the right track, install the pump and if that does the trick, leave well enough alone. If by rebuilding you mean bushings, that wont be required. You will absolutely have to replace some gaskets if you take the tower apart and if the regulator is apart it would be a shame to put the same 29 year old diaphram back inside. When you change the pump be sure and change the "sock" striner that attaches to the pump, they usually do not come with the pump and must be purchased separately. In addition, be sure all clamps are in good condition and hoses securely attached to the fuel pump, you will be dealing with considerably more pressure than with the original pump. Its a good idea to number or mark the two fuel lines that attach on the passenger side of the pipes at the filler neck to make sure these are reattached to the proper pipes. To keep from marring your paint, I would use old towels or similar to cover the rear deck around the filler hole kinda like a surgical site, there will be alot of twisting and turning trying to get the pump out and it would be easy to scratch paint.

Crossfire19822010-06-26 15:42:36

Fuel Pressure (9/21)
6/26/10 11:03pm

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

I'm lucky in the respect that my paint job looks good from 50 yrds. But I you were not kidding when you talked about getting that fuel pump out. I would rather take the dash out of the car. I've done that. Did not have much trouble getting it back in. Lit it off and got 7.5 pounds pressure. I guess I have to do some adjusting. Yes I did replace the sock on the end of the fuel pump and the rubber hose that connects it to the rest of the assembly.

What I was talking about is an article I read where they showed how to take the fuel pressure adjuster cover plate off and just doing the adjustments. Only reason I'm thinking about that instead of rebuilding at this time is I leave 9 July to Japan for a couple of weeks and ordering parts would mean I would not be getting anything done before I got back.

Fuel Pressure (10/21)
6/27/10 6:32pm

crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094

7.5 is really odd, Im sure GM had it set higher than that when it left the factory. I wonder if something is clogged somewhere or if the regulator has already been adjusted, the wrong way by a previous owner. 7.5 is not enough to feed the throttle bodies sufficiently. Any thoughts Dave?

Fuel Pressure (11/21)
6/27/10 6:44pm

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

7.5 may not be enough but it is a lot better than 5. Which is what I was getting. You could hear the injectors sound softer like the spray was finer after the pump was replaced. I also noticed that I could light up the tires from a stop now. Before if you tried to jump that hard on it, it just ran out of fuel. I will get it up to the correct pressure and balance the injectors. I notice that while the idle is smoother now it also has a slight surge I figure that could be unbalance injectors maybe. Again I stress it is only a slight surge.

Thoughts

Fuel Pressure (12/21)
6/30/10 9:16pm

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

Last post did not appear to go through forgive me if this ends up a dup. I want to know which rebuild kit to purchase the car only has 44K miles on it and the pressure reg is the only thing that seems not to be working correctly. I will use the Eckers part numbers so you can see what I'm talking about. I do not care where I purchase. Throttle body Rebuild Kit (completes front and Rear Units) #46324 or the fuel Regulator kit (both front and rear) # 46325

Do I do both or just one ??

Fuel Pressure (13/21)
6/30/10 10:34pm

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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2552

Where are you measuring the fuel pressure? Measure it before the TB's to make sure you're getting more than the pressure you need. Then measure on the line between the TB's. The pressure regulator is in the first TB so the line to the second one is regulated. 7.5 lbs. is not enough, you need around 11-12, I can't remember the exact number.

Dave

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Fuel Pressure (14/21)
7/1/10 2:58am

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

I'm measuring the pressure between the TBI's I have the DCS pressure gauge system installed. I do not have a fuel pressure gauge system that I can connect to the fuel line somewhere before the first TBI. I did just replace the fuel pump with a new 85 fuel pump. I figure that it is not likely that is bad. I guess I could take it to someone and have it put on a lift and have the fuel pressure checked. It would most likely cost less than buying a fuel gauge and connectors to tap into the line. By the way what should the pressure be if measured prior to the first TBI?

Fuel Pressure (15/21)
7/1/10 7:15am

crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094

The 85 pumps outputs a pretty high pressure, about about 40 psi from what Ive read, although Ive never actually measured my "before regulator" pressure. If you an get to a lift you could "T" in a gauge before the fuel filter and see what the pump is putting out to give you an idea where the problem may be. I agree with Dave, 7.5 is not enough for the car to run well.

Fuel Pressure (16/21)
7/1/10 11:01am

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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2552

THE '85 PUMP GIVES YOU AROUND 50 PSI. IF THERE IS A KINK OR A CLOG IT WOULD AFFECT THE VOLUME MUCH MORE THAN THE PRESSURE. THERE'S REALLY NOTHING TO GO WRONG WITH THE REGULATOR, EXCEPT THE SPRING AND IF IT FAILED YOU WOULD GET HIGH PRESSURE. UNLESS SOMEONE MESSED WITH THE SETTING BEFORE. YOU REALLY NEED TO REBUILD THOSE TB'S. I GOT REBUILD KITS FROM MY LOCAL CHEVY DEALER.

DAVE

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Fuel Pressure (17/21)
7/1/10 12:32pm

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

You said TB's so you are recommending doing both of them, correct?

I will be going overseas for a couple of weeks so ordering them is not a big deal. But if I decide to do it this weekend a Dealer may be a good source if they did not have to order it. What do you think the chances of that are? Never know until I ask I guess.

Fuel Pressure (18/21)
7/1/10 3:16pm

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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2552

Makes no sense to do one and not the other. My dealer had the kits in stock, but there were some addtional parts he had to order. Don't remember, it was about 6 years ago. If you have the '82 service manual, just follow that, it has good pictures and diagrams, I never did one before I did mine and it was not too hard, make sure you the injectors on the right side, they are different.

Good luck,

Dave

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Dave's '82

Fuel Pressure (19/21)
7/2/10 12:27am

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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2041

I rebuild the fuel regulator. Now I'm running about 13 psi. But have other issues. No big improvement over the 8psi. It feels like the car pulses when it is at idle and when it accelerates. It is hard to describe but the closes is pulsing.

I'm going to balance out the TB's this weekend and see if there is something else that I find wrong that I can fix.

Fuel Pressure (20/21)
7/13/10 10:49am

kwoody
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Tucson, AZ - USA

Vette(s):
1982 Black/Tan Leather Build Code C09E Bronze TTop CrossFire Fuel Injection L83 85 Fuel Pump Auto Axle 2.72 Firestone Firehawk Indy500

Joined: 7/11/2010
Posts: 415

I've had my 82 C3 for about 4 years. It sat in a field next to a pond in New England for 3 years. I drained the old gas. put in new gas and had some brake work done. It was and now is a good driver. After about a year, the idle went fast (1200 rpm) and the engine started surging during the first 5 mins after starting (cold). I shipped the car to Arizona and the car would barely stay running.
Took it to a local, he replaced the intake manifold gasket and was able to get it to pass the emission test here in AZ. I still had the high idle and surging. I replaced the chassis fuel filter. No change. I then replaced the fuel pump and the strainer/filter (in tank) That fixed the sluggish and most of the surging problem.
Before I left MA I had the AC serviced. It worked well there. Not Hot but removed the water out of the air. Once here in AZ the AC just barely got cool. Lots of 105-109` days out here. I found that the system was over serviced. I reduced the pressure in the system and recharged up to 55 psi. That stopped the compressor for short cycling causing the surges. So until the next "thing" I'm a happy camper. Normal idle, acceleration and AC operation.

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Fuel Pressure (21/21)
7/13/10 12:59pm

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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2552

Gilbert, try disconnecting the battery then re-connect. It will reset the computer (no codes), then drive around for awhile and see it helps. The pulsing is controlled by the computer. The temp. sensor may be bad, if the computer thinks the car is still cold you can have that problem. The temp. sensor is in the intake manifold, not the one in the drivers side head (for guage).

Never ends huh. Wits End

Wits End

Dave

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Dave's '82

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