fuel pump problems
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
fuel pump problems
85 vette....hate to start another thread, but the other one even confused me....now I have no codes....the fuel pump will turn on with the key...up to 38# and immediately drop to 0 with a click from the fuel pump relay...it's new too. wtf is the relay supposed to click?...never noticed that before... i did notice that the relay was made by the zipperheads....don't make anything good over there....do I need another one????.
Last edited by playsdixie; Sep 19, 2013 at 07:32 PM.
Safety Car
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http://forums.corvetteforum.com/1584961538-post4.html
It will if it is being turned on and off which it does when you 1st turn on the key.
The ECM only runs the pump for several seconds to prime the rails then it turns off.
The relay is only operated again when you crank the engine over and the ECM sees the signal
coming from the dist being rotated
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
Already answered
http://forums.corvetteforum.com/1584961538-post4.html
It will if it is being turned on and off which it does when you 1st turn on the key.
The ECM only runs the pump for several seconds to prime the rails then it turns off.
The relay is only operated again when you crank the engine over and the ECM sees the signal
coming from the dist being rotated
http://forums.corvetteforum.com/1584961538-post4.html
It will if it is being turned on and off which it does when you 1st turn on the key.
The ECM only runs the pump for several seconds to prime the rails then it turns off.
The relay is only operated again when you crank the engine over and the ECM sees the signal
coming from the dist being rotated
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
In your other post, you stated you were only getting 20 psi?
Has that now changed?
If you are running the pump fulltime through the test point and the pressure is low, then you are losing pressure somewhere upstream
Do the reg / injector leak down tests.
If the rail pressure comes up correctly but will not hold ,
then above tests also apply but the check valve in the tank may not be holding pressure.
You may also have a split in the line from the pump to the tank outlet that is bleeding off the pressure
Testing is the only way to determine the fault
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
Back to the basics.
In your other post, you stated you were only getting 20 psi?
Has that now changed?
If you are running the pump fulltime through the test point and the pressure is low, then you are losing pressure somewhere upstream
Do the reg / injector leak down tests.
If the rail pressure comes up correctly but will not hold ,
then above tests also apply but the check valve in the tank may not be holding pressure.
You may also have a split in the line from the pump to the tank outlet that is bleeding off the pressure
Testing is the only way to determine the fault
In your other post, you stated you were only getting 20 psi?
Has that now changed?
If you are running the pump fulltime through the test point and the pressure is low, then you are losing pressure somewhere upstream
Do the reg / injector leak down tests.
If the rail pressure comes up correctly but will not hold ,
then above tests also apply but the check valve in the tank may not be holding pressure.
You may also have a split in the line from the pump to the tank outlet that is bleeding off the pressure
Testing is the only way to determine the fault
fsm is asking me to pinch the return fuel lline and force the pump on...says it should get to 60...where should I piinch it off?..wondering how far I should go with this...replacing everything...manifold/injectors/ fuel rail/eg/spring diaphragm and regulator anyway....just like to know it ran before I started all this work...could be a leaking injector or fpr...just happened so suddenly....
although I get no codes...I couldn't get the burn off relay to go...thought maybe that has something to do with it...fsm says when you jump a and e, with the key on, and then off, wire should glow in 4 sec....doesn't happen....seems like I should get a code....
got a code 34 when this all started , but it doesn't read now when I read the codes...only 12....I haven't cleared it....where did it go? is my ecm playing with me???
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
You have to remove the dam around the filler neck to get to the two lines at the tank. They are the only place you can pinch the lines (feed and return) to test.
How long does it take to get your 38 psi?
How long does it take to get your 38 psi?
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
thanks, I knew I could get them there...just wondered if there was anywhere else...Paul
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Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
got around this am to get at the fuel return line...pinched it off...pressure went quickly to 38dropped to 20 and to 0 with the click of the relay.....fsm indicated to check leaking injector or cold start valve....it would have to be some leak to drop the pressure that quick...i'm thinking it's got to be the fuel pump..i'm thinking if there's a check valve, it's internal in the pump....with the 38 # spike, car will start to fire, but will not run...0 pressure....seen lots of threads complaining about crappy fuel pumps...this one's from ecklers, 3 months old..
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
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From: ft myers FL/Munising MI
this thread will be coming to an end soon....finally got the war dept to turn the key so I could quickly pinch the fuel pressure line...held pressure until I released.....somethings wrong in the tank...pump or the moron who installed it....i'll let you know....pulled it 3 times trying to fix the old sending unit...once for the fuel pump, once angain for the new sending unit....getting to be a pro at fuel pump removal...
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
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From: ft myers FL/Munising MI
end of this story....followed the gm manual to the bitter end....ended up being the very last thing on the trouble shooting chart....loose rubber connector on the fuel pump.....car now runs like a champ
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
If you're talking about a hose between the fuel pump and the tube on the fuel level sender, then that hose MUST be submersible fuel line. There was a "pulsator" there originally, but many people replace it with a piece of hose. This is the stuff you need:
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
If you're talking about a hose between the fuel pump and the tube on the fuel level sender, then that hose MUST be submersible fuel line. There was a "pulsator" there originally, but many people replace it with a piece of hose. This is the stuff you need:
Amazon.com: Gates Rubber Company 27093 5/16submersible Fuel Line: Automotive
Amazon.com: Gates Rubber Company 27093 5/16submersible Fuel Line: Automotive
now that it runs good again...going to tear it down...new injectors..intake/rails/runners/plenum/tb..all chrome..
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I had that same problem when I bought a new fuel level sender. I put some Ty-Raps on the fuel pump to raise the pulsator enough to make a good connection. That made me nervous because it seemed too shaky, so I replaced it with some silicone hose that I had. When I pulled it out a few days later the silicone hose was about twice the diameter it was originally. That's when I found out about the submersible hose. I found TONS of posts from people who used the wrong hose and had it dissolve in the fuel. Regular fuel hose is only resistant to fuel on the INSIDE.
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
I had that same problem when I bought a new fuel level sender. I put some Ty-Raps on the fuel pump to raise the pulsator enough to make a good connection. That made me nervous because it seemed too shaky, so I replaced it with some silicone hose that I had. When I pulled it out a few days later the silicone hose was about twice the diameter it was originally. That's when I found out about the submersible hose. I found TONS of posts from people who used the wrong hose and had it dissolve in the fuel. Regular fuel hose is only resistant to fuel on the INSIDE.
boy...does the car really run smooth...I always heard a little hesitation at idle...now perfect...smooth, no hesitation...i guess when you get the fuel pressure just right.....it goes...unfortunately now that i've got it to run so good...i'm building an intake/new infectors/rail/runners/plenum/tb...all chrome ..to be installed yet..new egr /regulator...setting it up in the garage....i'll pull it all out at one time....it's running soo good, i' hate to shut it down.
Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
Safety Car
Joined: Jan 2004
Posts: 3,556
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Thread Starter
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI