86GT won’t start (Page 2/3)
IMSA GT JUL 31, 02:06 PM
Oh and to answer your question, I don't think you can use a compression tester for fuel since the compression tester tests air, they have no seal between the gauge and hose. If you try to test fuel, I believe you'll fill up the gauge with fuel.

[This message has been edited by IMSA GT (edited 07-31-2022).]

sanderson231 JUL 31, 02:39 PM
Autozone et al lend out fuel pressure gauges

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

jwalker AUG 15, 06:33 PM
So I finally purchased a fuel pressure tester and I get nothing on the gage. I’m not hearing the fuel pump anymore either.
Patrick AUG 15, 07:27 PM
To rule out the fuel pump relay (as this procedure will bypass it) apply 12v to the fuel pump terminal of the ALDL port. (You can use power from the cigarette lighter.) If your pump doesn't run, you'll be needing to drop your tank.

[This message has been edited by Patrick (edited 08-15-2022).]

jwalker AUG 16, 05:53 PM
Okay, doing this, I hear the pump, so I need a new relay?
Patrick AUG 16, 06:03 PM

quote
Originally posted by jwalker:

Okay, doing this, I hear the pump, so I need a new relay?



For testing purposes, you can swap over the other relay located right beside it on the firewall. [EDIT] Looking back at your first post, I see you've already swapped over the relay. It's possible I suppose that both relays could be bad, but rather unlikely IMO.

Keep in mind, that even if the fuel pump is running, there may not be sufficient fuel pressure.

What's the fuel pressure when you're bypassing the relay?

[This message has been edited by Patrick (edited 08-16-2022).]

jwalker AUG 16, 06:17 PM
Should I connect the gage then trigger the fuel pump? Or gage, trigger pump, then turn it over?
jwalker AUG 16, 07:18 PM
So I triggered the fuel pump and tried to start it and still nothing registered on the gage. This will probably sound like a stupid question but my fuel pressure gage has a t connection with a clear tube coming off of it, the t has a push button, is this to drain fuel? Could I be using the gage improperly?
Patrick AUG 16, 08:01 PM

The button on the gauge is to relieve fuel pressure before disconnecting it... but it sounds like you have no pressure to relieve.

Have you tried disconnecting the fuel line to see if there's any fuel at all being pumped? You could even just push the center pin in the fuel line Schroeder valve to see if any gas squirts out.

And this may seem obvious, but people get fooled all the time. Is there gas in the tank... enough to immerse the fuel pump pickup?
jwalker AUG 16, 08:27 PM
When I changed the fuel filter I didn’t know what to expect as far as how much fuel would come out, not much did, but I thought maybe it’s a back pressure thing, idk. I believe the fuel gage is a little above an 1/8th of a tank. I’ll add some more fuel to be safe and I’ll check the valve tomorrow. Thanks for your advice.