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12/28/09 11:44pm - Original Message: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484

Ok the 81 just died and I think it's the fuel pump. I took the air filter cover off to see if fuel was coming out of the carb and I did not see any fuel. Is there a test I could do to ensure that the fuel pump is bad?

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12/29/09 12:57am - Reply: 'Fuel Pump'
dskopp
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Oak Creek, WI - USA

Vette(s):
1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
Posts: 1956
Why do you suspect the fuel pump.  Have trouble with it before?  Do you have ECM??

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12/29/09 8:25am - Reply: 'Fuel Pump'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
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The ECM on the '81 only controls idel fuel mixture and timing, so I wouldn't be suspecting a problem with the little black box for a no start.
You could have a bad pump, or a filter that has stopped up, either at the carb, or the "sock" in the tank.
You can check fuel pump output by taking the fuel line loose from the carb, and running some rubber hose from there into a fuel-safe container, Check the flow while cranking. You can also put a fuel pressure gauge(if you have one) on the line while it's off, and check actual pressure.
If you have good flow there while cranking, the float in the carb may be stuck, or the filter in the fuel inlet to the carb may be completely stopped up.
You say you saw no fuel in the carb, but were you working the throttle when you looked? The accelerator pump will squirt fuel when you work the throttle, but if you're just looking down in there, with the engine not running, you won't see anything.
hth


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12/29/09 10:48am - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484
Hey I did work the throttle and no fuel squirt. You might be right about some filter stop up. The car did set for about 10 years. A carb rebuild was on my list of things to do. I did drop the tank and replace the fuel sender so that part should be good. Where do I go for a diagram to show me were the filters are to check? I would like to pin point the problem. I will check the fuel pump today to see if it has some flow.
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12/29/09 11:15am - Reply: 'Fuel Pump'
VetteSpecialties
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Mounds View, MN - USA

Vette(s):
70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe

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Your car only has the filter in the carb.  Disconnect the fuel line at the carb, and test as Adam described.  If no fuel, try pressurizing the tank through the filler, which will show if the lines are clear.  Next is probably the fuel pump, which wouldn't be surprising after 10 years.  If the fuel pump tests OK, pull the fuel filter, and tap the carb in case the float is stuck.

Larry


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1/4/10 8:33pm - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484
Here's a update. Dskopp and I replace the fuel pump and the engine did not start. It seems to us the fuel is not getting to the pump. A few months back I drop the tank and replace the fuel sender so thats good. We put the compressor up the fuel line at the pump and blew it. We herd the air at the fuel neck but no bubbling yes there is gas in the tank?  Any idea's?
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1/4/10 11:00pm - Reply: 'Fuel Pump'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
A leak in the rubber hose from the tank pick-up could cause the pump to not be able to pick up the fuel. You might try pressurizing the the tank a little to see if fuel will run to the pump...

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Joel Adams
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1/4/10 11:44pm - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484
Hey thanks for the response. I will try to pickup something from Napa and check the tank.
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1/5/10 6:59am - Reply: 'Fuel Pump'
dskopp
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Oak Creek, WI - USA

Vette(s):
1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
Posts: 1956
I wil bet you that if you rebuild the carb all your problems will go away.  If it has never been done, I would suggest doing it (rebuild the carb).  After I had mine done I am having no problems whatsoever!!
Dan


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1/5/10 8:00am - Reply: 'Fuel Pump'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
Yeah, but....a new carb ain'ta gonna werk iffin there ain't no fuel gettin to it anyway, eh?
Not sayin the carb doesn't need some attention, but the problem as I unnerstand it, is there's no fuel at the pump...


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Joel Adams
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1/5/10 10:43am - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484
Yes my carb needs a rebuild but thats not the problem. There is no fuel going threw the line that connects to the crab.
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1/5/10 11:22am - Reply: 'Fuel Pump'
VetteSpecialties
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Mounds View, MN - USA

Vette(s):
70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe

Joined: 5/24/2007
Posts: 1031
I would wrap a rag around an air hose to make sort of a seal to the fuel filler, and blow into the tank.  If you see fuel leaking somewhere, that is the problem.  If you hear air, but do not move fuel, find the leak.  There is an old troubleshooting rule that says to recheck whatever you changed most recently.  Maybe your sender/pickup has sprung a leak.  There are two vastly different quality level units on the market.

Larry


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1/5/10 12:23pm - Reply: 'Fuel Pump'
aceinthehole Lifetime Member
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Valley Springs, CA - USA

Vette(s):
1978,Metalic Money Green W/Gold emblems,TH350 w/gear splitter,black & grey interior.1978,two tone,Metalic Rootbeer & gold ,Doeskin interior,auto. trans. 1981, Silver w/mirrored T-Tops,4 spd, charcoal interior.

Joined: 11/20/2005
Posts: 3618
Dave and I got together on Sunday to check this out and I have to say, it's the strangest thing I have ever seen. He put 5 gals. fuel in the tank but no fuel gets to the carb, and with all the hoses intact, we changed out the pump. Still not picking up fuel, we disconnected the fuel line from the pump and blew compressed air back up the fuel line to the tank to ensure that the pickup end of the fuel line was indeed immersed in fuel. We heard air coming out but no bubbling sound Confused. Now, we used a dip stick into the tank to guarantee we still had fuel and there was at least 6 inches deep, so you have to wonder, could it be possible for the bladder to deform in such a way as to dam up more than 5 gals. of fuel away from the pickup tube. Dave just pulled the tank and replaced the fuel pickup assembly last month. We're now looking at replacing the fuel tank because there seems no other recourse. What do ya think guys? 

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1/5/10 1:35pm - Reply: 'Fuel Pump'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
There was no mention of there being any bladder distortion when the sender was changed, so I didn't think that would be an issue. It could very well be the problem....put some more fuel in it and see....

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Joel Adams
C3VR Lifetime Member #56    
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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1/8/10 7:49pm - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484

Ok hookup a fuel can to the pump and it started working. So I reconnected the lines and it ran for 1 min then stop. It must be the tank or the rubber fuel hoses the tank.  I guess I will redrop the tank and take a closer look at everything  and hope I fine something?

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1/10/10 12:50pm - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484
Questions? Drop the fuel tank and did not see anything unusual in the tank. Put a fuel can up the fuel line and the car started. So the fuel pump and the fuel line leading up to tank are good. The fuel sender is new. Now what? Is there a test for the fuel sender? The only thing that gives me pause is the bend on strainer tube on the sender.
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1/10/10 4:11pm - Reply: 'Fuel Pump'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
Can you blow thru the sender and verify it is open/clean?

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Joel Adams
C3VR Lifetime Member #56    
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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1/10/10 10:42pm - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484

Yes I can blow in the tube and it is not clogged. Each time that I drop the fuel tank I took out about 10 gallons of gas. Could the angle of the stainer tube have anything to do with it? I am about to give the car to the vette mechanic to let him figure it outCensored

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1/10/10 11:32pm - Reply: 'Fuel Pump'
eddie20875 Lifetime Member
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Lanoka Harbor, NJ - USA

Vette(s):
1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c

Joined: 12/21/2006
Posts: 828
i may be wrong but there should be a rubber hose that goes from the tank to the metal fuel line that runs to the front of the car. is it possible that the rubber hose had come apart inside and on suction has a flap that blocks the flow. blowing into the tank wouldn't show this. maybe try disconnecting that hose from the tank a blow through it that way. just an idea


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1/12/10 9:23pm - Reply: 'Fuel Pump'
ossw1
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Rocklin, CA - USA

Vette(s):
1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

Joined: 4/2/2005
Posts: 484
Yessss, I think I have the problem with the fuel. I thought the sender unit pick up tube look wrong. Talk with Aceinthehole he suggested that I take a wire bend it the same as the fuel sender to see how it looks in the tank. Well the sender pickup tube bend at a 285 degree angle which put the strainer end sticking up out of the fuel.  Which would explain why each time I drop the tank I got 10 gallons of fuel out. When the tank was half fuel the sender tube was sticking up past the half point. Lets see what happens when I put the tank back in.
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