MORE Fuel Pressure Problems

[Four-Four-Two]

short history:
Car ran good with original pump.

took it out, and installed walbro 307 & hotwire. I didn't know that you were supposed to chuck the pulsator and replace with hose. the pump slid off of the pulsator, so it was pumping the gas, but spitting it back in the tank.

I put the stock pump back in for the time being while I researched why my car wasn't running. ( before i found out about pulsator) The car ran fine, no problems.

We put the walbro 307 back in and replaced pulsator with hose. Now the car cranks but it wont start. When I turn the key ON, the pump primes and fills the rail, then turns off. I let the pressure out of the rail, with the key still ON, but the pump doesn't turn back on to fill the rail again. I have to crank it before it will fill back up. Plus, it has hardly any pressure.
I plugged the two connectors together to make the pump run continuously, and it maintains good pressure.

Why is it that the pump wont turn on after the initial pressure build up before car is cranked?

 

[salvageV6]

I think the ECM will only do the initial prime and then it expects you to start the car. If you siphon off the pressure you will have to cycle the key or crank the car to rebuild it.

ECM is what keeps the pump running continuously after the car has started.

Hope that makes some sense.

I assume if you leave the pressure built up by the 307 it will start the car no problem, right?

 

[Four-Four-Two]

Originally posted by salvageV6
I assume if you leave the pressure built up by the 307 it will start the car no problem, right?

Thats actually my problem, the car won't start! It just cranks.

 

[salvageV6]

What hotwire kit? Was the stock pump hotwired too?

What fuel pressure are you getting with both pumps?

 

[WarpSpeed]

You have to turn the key off for 15-30 seconds for the pump to reprime. Also, Cranking it alot will produce oil pressure, and when the oil pressure switch trips, it will cause the fuel pump to run.

 

[86gn]

Originally posted by Four-Four-Two
.
I plugged the two connectors together to make the pump run continuously, and it maintains good pressure.

What 2 plugs

 

[Four-Four-Two]

Salvage- I bought the pump and hotwire from PTE. I'm not sure on fuel pressure as of yet, I have to get a gauge from work on Monday. With the Walbro right now, it spits like an ounce or two of gas out, with hardly any pressure at all, like 5psi at most. When I pluged the pump in to run continuously, it had good pressure when it sprayed out.
With the stock pump, I was getting enough to run the car.

86 GN, there is a small connector (male end) hanging loose near your altenator, plug that into the female end that your hood lamp plugs into. The pump will turn on and run constantly.

 

[Chuck Leeper]

No/LO PSI??

When you put the hose in place of the pulsator, you DID use the clamps that were supposed to be in the kit, didn't you?? You were to cut off the end of the fuel supply tube to get rid of the necked down part. Then you put the pump in the hanger w/ the rubber insulator under it, cut the hose to a length that is just long enuf to hold the pump down in the hanger, remove the pump and install the hose and clamps, [loose on the clamps for now], then re-install the pump in the hanger, push the pump away from the metal tube so the pump is titely held in place and tighten the clamps.
If you installed the hose the same way as the pulsator, then the hose is leaking and you will have to drop the tank, install the hose w/clamps and recheck everything.
You didn't cross the lines at the frame end of the tank tubes did you?? If you did, you will have to get that corrected when the tank is down.
You did change the filter, RIGHT?? It's not in backwards, is it??

 

[Steve Wood]

Think Chuck pretty well has summed it up.

It won't start if the fuel pressure is too low. The current behavior is correct. Power for two seconds and not again just because you released the pressure.

Hose not clamped in the tank, lines acrossed when you reinstalled the tank, plugged filter...those seem most likely to me.

Oh, you do have enuf gas in the tank to prevent sucking air, don't you?

 

[Four-Four-Two]

plenty of gas
brand new filter, installed correct direction.
we did use the clamps on the hose.

what we did was take the pulsator out, we put the hose from the end of the pump all the way up to the sending unit.
Chuck, what do you mean by "cut off the end of the fuel supply tube to get rid of the necked down part"? Why isn't any of this stuff in the instructions. We have already dropped the tank 4 times now.

 

[salvageV6]

Chuck is talking about the tubes that come out of the tank hanger sending unit.

3 pipes all have swaged bulbs on them that sorta neck down the lines. People cut them off behind that part I believe and hook the hose further up on the cut off line where the pipe is full ID.

I never did it and I don't think that's your problem right now.

Now, Was the stock pump hotwired too? Have you tried the pump after the hotwire kit?

Check the fuse in the hot wire kit. Check also the FP/INJ fuse in the fuse box.

 

[Four-Four-Two]

the factory pump was hooked up to hotwire, ran fine.
I also disconnected the hot wire and tried with the factory wiring and that didn't work ethier.

Going to check fuses in a little bit.

I guess the main problem is that the pump turns on to prime, but when you turn the car over, it wont turn back on.

 

[Steve Wood]

Car should fire and run off the prime.

Do something simple like take the fuel pump test lead and connect it to the terminal on the back of the alternator with a jumper. This will run the pump full time rather than two seconds only. Does this give you enuf pressure to start the car?