Fuel pump won't prime after running
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
Fuel pump won't prime after running **FIXED**
OK, so yesterday after the car sat for 4 days it fired right up. Fuel pump primed like it's supposed to and hte car lit right off. Go to lunch, 4 hours later and the pump doesn't prime and it cranks for a long time before starting. Same when it came time to go home.
So, likely fgoing to be the relay... where is it?
So, likely fgoing to be the relay... where is it?
Last edited by Bobzilla; Oct 8, 2010 at 09:08 AM.
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
88 4+3 manual trans Z51 coupe. I understand it's on the firewall? Not sure which one. Obviously it'll be the one NOT clicking, just trying to make it a little easier.
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
iF the car sits for a few days, the pump primes and it fires right up. If it's been driven recently, it won't. I haven't checked fuel pressure yet, but the regulator is not bleeding out through the vacuum line.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Yours is an intermittent problem, probably heat related. Even if you ran 12V to it and the relay works that wouldn't tell you, definitively, if yours in bad or not. I believe HEAT is an ingredient here.
During times when the engine takes a lot of cranking to start, once it does start, disconnect the relay and if the engine continues to run, then replace the relay.
Also, when you first turn the key to ON but DON'T CRANK the engine, you should be able to hear the pump energize - hum/buzz.
There are testing procedures in the FSM but, considering how inexpensive the relay is, it might be, over-all, easier just to replace it.
Jake
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
The pump is probably 22 years old also, I agree with Jake on it being a heat problem, once the pump gets cool it will work, but after it heats up it won't work again till it cools off. Makes sense to me but the FSM gives procedures to check for sure. Of course it probably wouldn't hurt to just replace the pump if it is the original and you have the money.Just call it (preventive maintainence)...WW
Last edited by WW7; Sep 26, 2010 at 07:26 PM.
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Le Mans Master
Joined: Aug 2000
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From: Australia
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
The pump is probably 22 years old also, I agree with Jake on it being a heat problem, once the pump gets cool it will work, but after it heats up it won't work again till it cools off. Makes sense to me but the FSM gives procedures to check for sure. Of course it probably wouldn't hurt to just replace the pump if it is the original and you have the money.Just call it (preventive maintainence)...WW
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
So... got a new pump and strainer. Simple install. Pump primes every time. Now that the pump is actually holding pressure, the pressure regulator is now leaking. lol.... I shoulda known!
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
You may have also had a bad check valve in the pump.
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
I know the pump itself was done... fuel pressure was weak and it would only prime when cold. Plus it bled down pressure quickly after shutoff. I had checked the FPR hose intially and it wasn't leaking from there at that time.... but now that the check valve is working and the pump holds pressure, now it does.
I can't complain. It's 22 years old with 143k miles on it. Stuff breaks. At least the parts are cheap. Much better than my 16 year old Japanese car I had previously....
I can't complain. It's 22 years old with 143k miles on it. Stuff breaks. At least the parts are cheap. Much better than my 16 year old Japanese car I had previously....
Thread Starter
Racer
Joined: Aug 2010
Posts: 344
Likes: 0
From: Lebbrownsville Indiana
One $30 FPR later and she instantly fires up. Runs amazing. I'd guess the combination of the 22 year old original pump, plus the original strainer that was just about varnished over, plus the leaking fpr had sapped some power and performance out of it. Car runs smoother, stronger and happier.
One system fixed and up to snuff.... now on to the next one!
One system fixed and up to snuff.... now on to the next one!
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
One $30 FPR later and she instantly fires up. Runs amazing. I'd guess the combination of the 22 year old original pump, plus the original strainer that was just about varnished over, plus the leaking fpr had sapped some power and performance out of it. Car runs smoother, stronger and happier.
One system fixed and up to snuff.... now on to the next one!
One system fixed and up to snuff.... now on to the next one!
