New Fuel pump - won't start!
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
New Fuel pump - won't start!
Well I just installed a new Walbro fuel pump in my 86 roadster. Followed the Forum instructions which were just great. However, after I got if all back together, it would not start. Assuming a bad pump, I removed the new Walpro and reinstalled the AC Delco - STILL WON'T START.
I double checked all the wiring and connectors, all looked okay and tight. Tried priming the plenum which makes it spit, but it won't fire. I'm pretty sure it is not getting any fuel. Any suggestions?
I double checked all the wiring and connectors, all looked okay and tight. Tried priming the plenum which makes it spit, but it won't fire. I'm pretty sure it is not getting any fuel. Any suggestions?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Back to basics.
Can you hear pump prime when key turned on?
If not ;elec problem
(12v to the G terminal of the ALDL under the dash will run the pump , bypassing the relay)
If it runs
Have you got pressure in the fuel rails?
If you don't have a gauge, CAREFULLY pushing the valve on the rail (under screw on cap, pass rear )will squirt fuel if pressurized.
Can you hear pump prime when key turned on?
If not ;elec problem
(12v to the G terminal of the ALDL under the dash will run the pump , bypassing the relay)
If it runs
Have you got pressure in the fuel rails?
If you don't have a gauge, CAREFULLY pushing the valve on the rail (under screw on cap, pass rear )will squirt fuel if pressurized.
Last edited by rodj; Feb 23, 2007 at 06:26 PM.
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Back to basics.
Can you hear pump prime when key turned on?
If not ;elec problem
(12v to the G terminal of the ALDL under the dash will run the pump , bypasssing the relay)
If it runs
Have you got pressure in the fuel rails?
If you don't have a gauge CAREFULLY pushing the valve on the rail will squirt fuel if pressurized.
Can you hear pump prime when key turned on?
If not ;elec problem
(12v to the G terminal of the ALDL under the dash will run the pump , bypasssing the relay)
If it runs
Have you got pressure in the fuel rails?
If you don't have a gauge CAREFULLY pushing the valve on the rail will squirt fuel if pressurized.
Do the above as suggested amd report back.
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Don't heat pump initiate when I turn key, but did not hear it when it was running either. No fuel pressure at the rails.
Can you walk me thru -12v to the G terminal of the ALDL under the dash to run the pump , bypassing the relay?
If I do this how will I know if the pump is running; will I hear it or do I just recheck the pressure at the rails?
Can you walk me thru -12v to the G terminal of the ALDL under the dash to run the pump , bypassing the relay?
If I do this how will I know if the pump is running; will I hear it or do I just recheck the pressure at the rails?
Safety Car
Joined: Nov 2004
Posts: 4,991
Likes: 5
From: The Pines South Jersey
Well I just installed a new Walbro fuel pump in my 86 roadster. Followed the Forum instructions which were just great. However, after I got if all back together, it would not start. Assuming a bad pump, I removed the new Walpro and reinstalled the AC Delco - STILL WON'T START.
I double checked all the wiring and connectors, all looked okay and tight. Tried priming the plenum which makes it spit, but it won't fire. I'm pretty sure it is not getting any fuel. Any suggestions?
I double checked all the wiring and connectors, all looked okay and tight. Tried priming the plenum which makes it spit, but it won't fire. I'm pretty sure it is not getting any fuel. Any suggestions?
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Remove your gas cap. Have someone turn the key on while you listen at the gas filler hole. You will be able to hear it run clearly. If it doesn't then check your wiring at the pump connection for 12v. If no voltage there, then it may very well be your fuel pump relay that has gone bad. You need to invest in a Helms manual for you car. It will pay for itself. MAybe someone will jump in here with which wires carry your 12v to the pump pig tail and where the relay is located on your 86.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Remove the fuel pump connector above the fuel pump. Use a jumper wire from the + side of the battery to terminal G of the ALDL (lower left terminal). Go to the fuel pump with a voltmeter and test the harness terminal for 12v. There should be 12v there and if not then the problem is not the pump.
There is a tan w/white stripe wire, red, and black. I think you want to test the tan w/white stripe. I am away from my manual, but from memory I think that is correct. If not test all.
There is a tan w/white stripe wire, red, and black. I think you want to test the tan w/white stripe. I am away from my manual, but from memory I think that is correct. If not test all.
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Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
I can also hear the relay engage and the pump prime when the key is first turned on.
The computer primes the system then the oil pressure switch supplies power direct to the pump when the engine is running.
As stated you first need to verify that you have power to the pump , the connection on the pump is good and that the pump will run when hot wired through the G terminal before checking other.
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Broken Wire Discovered !
Checked voltage thru ALDL with no positive results. Rechecked wiring harness coming from top of tank and discovered a broken hot wire under the wiring insulation (20 year old little wires are brittle). Repaired wire and car started. 
Thanks for all the positive input.
Now I think I am going to test the new Walpro fuel pump before I reinstall it. Can I take it to an AutoZone shop to have it tested? Any ideas on this?
Thanks for all the positive input.Now I think I am going to test the new Walpro fuel pump before I reinstall it. Can I take it to an AutoZone shop to have it tested? Any ideas on this?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
As you stated your old working pump also did not run after you disturbed wires.
Your problem has been (so far ) electrical , not pump operation
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Checked voltage thru ALDL with no positive results. Rechecked wiring harness coming from top of tank and discovered a broken hot wire under the wiring insulation (20 year old little wires are brittle). Repaired wire and car started. Thanks for all the positive input.
Now I think I am going to test the new Walpro fuel pump before I reinstall it. Can I take it to an AutoZone shop to have it tested? Any ideas on this?
Thanks for all the positive input.Now I think I am going to test the new Walpro fuel pump before I reinstall it. Can I take it to an AutoZone shop to have it tested? Any ideas on this?
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Fuel pump check?
If I run an alegator clipped wire from the battery + terminal to the hot lead on the new pump (out of the car) and a wire from the pump's ground lead to the frame, shouldn't the pump run? If I just check it this way to see if it runs will this hurt it or is there a better way to check it without taking it to a shop? Let me know what you guys think.
Thanks much.
Thanks much.
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Tested Pump - works fine.
Tested the new Walbro pump as described above and it works fine. I'm going to reinstall it.
Again, thanks to all for the great advice. You guys saved me a bunch of time and dealer related headaches.
Again, thanks to all for the great advice. You guys saved me a bunch of time and dealer related headaches.