Fuel pressure lea down...yipes
Thread Starter
Racer
Joined: Jun 2000
Posts: 428
Likes: 1
From: Friendswood Texas
Fuel pressure leak down...yipes
Lately my 86 won't start on the first crank when it has been driven and then sits for a couple of hours. Starts first time in the morning when it's cold. So I'm thinking leaking fuel injectors like I've read on the forum many times. But I have new FMS 24# with only about 1000 miles on them! I put the fuel pressure gage on, turn her on (pressure goes to 38 psi). Turn her off and pressure leaks down to 10 psi in less than 3 minutes. seems to hold at 10 psi.
Question: Is there a check valve at the fuel pump that may be bad? Could this cause my starting problem?
Man I hate to think it's injectors.
Any help would be greatly appreciated.
BTW It runs and idles great once it starts.
[Modified by Mike263, 8:21 PM 8/28/2002]
Question: Is there a check valve at the fuel pump that may be bad? Could this cause my starting problem?
Man I hate to think it's injectors.
Any help would be greatly appreciated.
BTW It runs and idles great once it starts.
[Modified by Mike263, 8:21 PM 8/28/2002]
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Fuel pressure leak down...yipes (USPRIDE)
Do what eric said, if the problem is still there, then you may have an injector hanging open. But I bet it doesn't come down with the line pinched.
I have FMS #24 too. Mine will hold pressure for a good 8 hrs sometimes its still at pressure overnight.
Hope you find it.
I have FMS #24 too. Mine will hold pressure for a good 8 hrs sometimes its still at pressure overnight.
Hope you find it.
Instructor
Joined: May 2002
Posts: 196
Likes: 0
From: hastings mn
Re: Fuel pressure leak down...yipes (Mike263)
Had the exact same problem, installed the same injectors as well, problem was still there. It turned out to be the Fuel Pressure Regualator, which, when tested at the intake line, didn't leak at all. The GM service shop had to hook vacuum up to it, in order to determine it was leaky. I installed the new one myself and it's been smooth starting ever since.
Thread Starter
Racer
Joined: Jun 2000
Posts: 428
Likes: 1
From: Friendswood Texas
Re: Fuel pressure leak down...yipes (USPRIDE)
Any luck on solving the problem yet?? :chevy
Thanks to all who offered help.
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Thread Starter
Racer
Joined: Jun 2000
Posts: 428
Likes: 1
From: Friendswood Texas
Re: Fuel pressure leak down...yipes (USPRIDE)
How tough was it to replace the fuel pump? Any words of wisdom??
Thanks!!!
Thanks!!!
Actually it was fairly easy. The pump and the gas gage sending unit are combined (with associated steel fuel lines) into a single, removable unit refered to as the "sending unit" in my manuals.
Remove the gas door.
Remove the rubber splash shield.
Now you have to be careful - disconnect the two fuel lines from the "sender unit". Lossen the clamps and pull them off the sending unit. Be careful not to damage the rubber lines getting them loose. They are an integral part of the fuel lines that run to the engine and I understand these lines are no longer available.
Unplug the electrical connection located just under the rear edge of the opening in the body.
Remove the fuel vent line.
Remove 9 bolts and lift out the "sending unit".
Disconnect the ground and supply electrical connections from the pump. Remove the fuel pump by pushing the pulsator up the on the fuel supply tube and pulling the pump off of the bottom suppport. Be sure to replace the strainer "sock" on the bottom of the pump when you put in the new pump.
Installation is the reverse of removal.
The pump I bought did not have the same electrical connections as the original, but it came with instructions and parts to convert.
A shop manul with drawings/photos will give you better instructions.
Good luck.
Racer
Joined: Oct 2000
Posts: 476
Likes: 0
From: Socorro New Mexico
Re: Fuel pressure leak down...yipes (Mike263)
After reading a few of the posts on this subject, I am starting to understand maybe why mine won't start after it heat soaks for about 15-20 minutes. If the pressure is bleeding off back through the regulator, could this cause vapor lock? The hot start problem was there with the old injectores and was still there after I put in a new set. The hot start problem does not happen everytime, but enough to make me antzy.
