Quote:
Originally Posted by senorv47
Just a question I'm not able to find an answer to. Does the fuel system on an 86 have a check vavle to maintain pressure between starts?

Ok, finally got that fuel issue good, at least I thought but yesterday I drove it over to Walmart and back and decided to stop and have some lunch ansd wgen I got back in the car it started and when I put it in gear and started rolling back it died. Starts but won't idle, lots of popping from the throttle body. Here's what I've done to try a diagnose this:

Checked fuel pressure good at 40 lbs
chacked distributor rotor - good
plugs for spark - good
fuel pump relay new
GM tester code 12 - no issues
Vacuum lines in good order
changed fuel injectors about three weeks ago (leaky injector)
checked fuses - good

So can anyone give me some insight on this issue


Thanks,
Manny

Update 6 August 2007:

Just an update that might help those members who are still having problems. I read somewhere the last couple of days about an oder that come from the car (finally got it started after replacing the fuel pump but still was not idling) like rotten eggs, well it point to the O2 sensor and guess what? That was part of the problem, after I change that then it idles but only with the MAF disconnected, so I still have an issue with the MAF but now at least I know what it is. Thanks to all who help on this thread. I think I can handle it now.

 

From what I remember yes but it is inside the fuel pump.

 

although I'm not sure it's a check valve per se. it will bleed down. The pump runs for about 50 sec. when the ignition key is turned on. You have to turn the key off for over 5 sec. to have it turn on again for 50 sec.

 

Except for the 50 seconds, more like 2 seconds.

 

Except for the 50 seconds, more like 2 seconds, and except for the 5 seconds is more like 10 seconds.

BUT! A leaking or defective check valve isn't the only place fuel system pressure can bleed off. Pressure can be relieved from three different places. As you suspected, the check valve in the fuel pump, the least serious and least in need of repair, each of the 8 fuel injectors, and finally the fuel pressure regulator. I believe your FSM has the tests to isolate which of the three is your problem. The tests involve pinching the inlet and outlet fuel hoses while observing fuel pressure. You will also find the procedures if you do a search. The tests have been written up many times, including several by myself.

RACE ON!!!

 

Thanks dude, I appreciate everyone input on this. I just changed out the injectors and the problem got alittle better but there is still a pressure issue somewhere. I have to crank it at least twice before it will start whether cold or hot By the way it's an 86 Corvette

 

If it hasn't been changed, the fuel pressure regulator might be a good place to start, it's just a rubber diaphram, and they go bad, and they are pretty cheap.

 

If you don't have a fuel pressure gauge, buy or borrow one. My fuel pressure loss was at the pulse damper above fuel pump.

http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf

 

Mine too

 

Yes, but don't replace anything until you do the tests and discover a defective part. Throwing money at a problem only wastes your hard earned. If you have money to burn, take it to the stealership.



Dude??? Hey Bubba, according to this, I don't see where you have even checked the fuel pressure. Extended cranking can have multiple causes. Have you checked the pressure before touching the car after letting it sit? What happens to the pressure when you turn the ignition to "On"? When cranking. If they bleed down, how long does it take? Is the priming function working? A little trouble shooting can save a lot of money. I hope you had good cause for changing those injectors.

RACE ON!!!

 

Apologize for the Dude thing, just a friendly Maryland thing, anyhow, I took it to a mechanic for diagnosis and they tell me and documented that the fuel pressure was good and the fuel pump was good (haven't tested it myself) and that I had one or two leaky fuel injectors. They wanted to charge me $1400.00 (which included all the injectors plus labor) to fix it but I found some injectors from a fellow forum member and they ohmed out good and so I did the work myself. I replaced all the O rings and caps on the injectors,then replaced the O-rings on the fuel rail, and gaskets on the runners. So while the problem did get better (only have to crank two times versus five, but sometimes it cranks the first time) the problem still exists. I'm going to buy my own pressure tester and follow the FSM procedures and see what happens.
I do however appreciate all the feedback because it gives me a warm and fuzzy that I have my fellow experienced forum member to help me. If there are any other helpful hints out there, I would be welcomed to hear them. Thanks again guys and gal's great feedback!!

 

ttt Any other comments?

 

What comments are you looking for:
If you follow the pressure test, then get back with the results, there might be addl comments or help, but you'll need to continue the process.... first...

 

I mean't helpful tips as I continue the tests

Thanks

 

Yes. Do the tests. Start as redirected, below, to see if you even have a leak down problem. Once we get those results, we can proceed from there.


RACE ON!!!.

 

Did the test, with out touching the car I have 0 pressure. When I turn the key on I get 42 lbs and bleed down occurs 2 seconds later. with the car running I get a consistent 38 lbs of pressure to the rail. Any further thoughts?

 

I have an 86e with the very same problem.
I checked the fuel pressure with a gauge, and the fuel was bleeding off right away. I removed the fuel pump from the tank, and changed the pulsator, and the sock. I changed the sock on the pump, and when I grasped it, prior to changing it, it crumbled like paper.
the pulsator is from a 90, and it was better for a while.
I changed the quantity sender to a 90, and reassembled it with a new ground wire, new gasket.
I changed the FP regulator because I thought it was that, I put a holley one on it.
it might soon have been that because the red silicone rubber was delaminating from the glass cloth of the diaphragm.

I changed the fuel pump relay because the prime fuel was not present after the 2 second prime sequence. I had power at the relay terminals.
I changed the injectors last year, I also changed the manifold, heads, runners, and plenum. it was an engine upgrade.
It still bled down.
The gauge seemed to fluctuate a lot at idle, and dipped below 40 psi when goosing the throttle.

UPDATE:
Changing the fuel pump has helped immensely. The car runs better, and the fuel doesn't seem to drain back to the tank.

After the pump change, the needle is steady at idle, and when the throttle is moved rapidly, the fuel pressure does not go down, but increases 2-3 psi, then rises to 45, then settles down at 39 PSI.
The cat seems to run cooler.
There is no hot hot hot smell coming from under the car.
The car idles smoother, and when the throttle is closed rapidly, the engine does not die.
When starting it cold, the starter cranks a little longer than an instant start, but no where near the full minute it ws doing before.
The acceleration is better as well.

 

Just keep throwing parts at it.


Cut and pasted from my PMs so the rest of the forum would be aware of what he had been advised.

RACE ON!!!

 

CFI, I did find a leak where the cold start injector goes into the fuel rail and I think I've got that taken care of. I will report more when I get home this evening.

 

Changing a FPR on a 20 year old car is not necessarily throwing parts at it. While not a maintainance part, it probably should be. But I agree, "easter egging" parts is expensive and not very wise.