Fuel pump problems

[Erics88]

Hello. I'm a new member to the form and to the v8 ranger. I've always wanted to do one. Been a Ford person all my life, and everyone and anyone can do v8 Chevy. Anyway, I have a 88 ext formerly 2.9L automatic, now it's a Explorer based EFI 5.0L with a E303 and AOD. 90 Mustang harness and computer. Now for the problem that I'm having, the fuel pump either cuts out, it's gone bad, or the computer will not support two pumps. I can drive it around for a little while, then the truck sputters, then dies. It acts like it's running out of fuel. I ran it today with a pressure gauge, and that's exactly what happens. It will die, try to start it, and the pressure is to low to keep it running. If I wait around 20 to 30 mins., the pressure is good and the truck fires and runs. I replaced the pump in the tank, but not the high pressure pump for the build, because I removed the front tank, and replace it with a ranger rear tank. The truck has right at 90K on it, and it ran great and with no problem 3 month prior to the swap. Any ideas about the Mustang computer not being able to support to pumps? Do I need to put a high pressure in the tank and remove the in-line pump? Or do I need to hot wire the in-line pump? Thanks and look forward to many chats on the form. Thanks in advance

[cgrey8]

EFI pumps don't generally "like" being inline with each other. They flow what they flow and you can't really make them flow more by putting another pump ahead of them. I would recommend buying a high flow intank pump and running a single pump system. Walbro 155lph pumps and TREPerformance 255lph pumps can handle most any mild to moderate build out there with no problem.

As for the EEC, it wouldn't have anything to do with this. It either triggers the pump(s) to run, or it doesn't. The limiting factor in the setup would be how many amps the fuel pump relay could get to the pump(s). My guess is you have some mechanical problem that's causing the lines to either collapse (i.e. one pump is sucking the other dry and flattening the line) or one pump is overheating and shutting itself down which nearly kills flow and pressure to the engine even if the other pump is running.

Another option is to just try 1 pump and see how well 1 or the other works. You are describing a fairly mild build. Even the stock Ranger 88lph pump could probably keep have kept up without too much trouble.

[Erics88]

[quote="cgrey8"]EFI pumps don't generally "like" being inline with each other. They flow what they flow and you can't really make them flow more by putting another pump ahead of them. I would recommend buying a high flow intank pump and running a single pump system.


I believe that the 88 and older trucks come factory with two pumps. Low pressure in the tank and a high pressure on the frame rail. Thanks for the info about the EEC. I didn't think that it would really know the difference. But, being a Mustang EEC that only had one fuel pump, maybe the voltage was not enough. About the over heating problem, I thought that was the problem, but I let the truck set in the driveway and run, it never dies. I would think that driving down the road would cool the pumps. Or is there more stress on the pumps? They would pump the same no matter what, wouldn't they?I think I will be putting a high pressure pump in the tank and eliminate the in-line pump. One more problem not having to worry about down the road. Thanks

[cgrey8]

Low pressure feeding a high pressure pump is no problem. It's when you got 2 high pressure pumps back to back that causes problems. If what you got now is a low-to-high setup, then that hopefully isn't the problem after all. But I still say the 2 pump setup isn't necessary. The aftermarket TREPerformance 255lph pump I have replaced my stock Ranger 88lph pump. Although I can't say I'd get that high of a capacity pump again. The high flow rate of this pump creates vortexes and sucks up air on sharp turns if the fuel level gets too low and the stock pump never used to do that.

[usmcrp1044]

About the over heating problem, I thought that was the problem, but I let the truck set in the driveway and run, it never dies. I would think that driving down the road would cool the pumps. Or is there more stress on the pumps? They would pump the same no matter what, wouldn't they?I think I will be putting a high pressure pump in the tank and eliminate the in-line pump. One more problem not having to worry about down the road. Thanks

An engine will use much more fuel under a load then just idling. Free-reving an engine to 2,000 rpm's will use very little fuel compared to driving up a hill at 2,000 rpm's. And a fuel pump is usually cooled more by a return line then air passing over them. Without a return line, the fuel dead ends in the line until the engine is able to use enough of it.
With the return line, there is constantly cool fuel passing through the pump.

Have you checked your fuel filter at all?

[Erics88]

No, I haven't checked or replaced the filter. I thought of that, but why would it be a consistent 25/30 mins. before it would start again. I thought that I heard a click that came from the EEC. I have already checked the EEC relay and the fuel pump relay and they both click when the key is turned on. That's why I was thinking that the EEC couldn't support the two pumps. Does the EEC have a relay inside of it? Not pulling any code, so could the EEC be bad?

[cgrey8]

No, the EEC is 100% solid state. There's no internal relays.

[Erics88]

Ok. Thanks. Would it be best to replace the low/high pumps with a high pressure in the tank?

[cgrey8]

I can't honesty say that's "best". All I can say is that setup work well for me as does it work well for a number of other people. Amazingly, the stock Ranger pump can keep up with a 300hp engine and do it with a 15% safety factor.

I'd still be running the stock Ranger pump now if it was strong enough to overcome my adjustable FPR. My aftermarket adjustable FPR bleeds the fuel pressure down in about 1-2 seconds after the fuel pump has turned off. The stock FPR would hold fuel pressure for days after the engine had been turned off. So when I went to crank the engine, the stock pump had to prime the system back up with pressure before the engine would crank. So either I held the key to start the engine longer or I had to cycle the ignition at least twice before attempting a crank to give the fuel pump a few seconds head start to get the pressure up.

Once I installed to the TREPerformance 255lph pump, that was no longer a problem. That high output pump is more than capable of getting the fuel line up to pressure without me having to manually prime the fuel line before cranking.

If I knew then what I know now, I'd have kept the stock FPR and stock Ranger fuel pump. The reason I bought the adjustable FPR was to diagnose a problem that I thought was related to the stock FPR...but wasn't. But it took me getting the AFPR to know that. Live-n-learn.

[Erics88]

Cgrey8, was your truck a factory one pump set up? Is there anyone else here that ran a factory dual pump set up with EFI? Is it possible that the engine is more than the pumps can handle? I have a 88 F150, and it has the exact same set up(fuel pump wise). When I replaced the pump in the tank in the ranger, I put a F150 pump in there. The High pressure in-line pump is the same as my F150. I wouldn't think that a 89 H.O. short block 40 over, GT40 heads and a explorer intake, E303 cam, and headman headers 2.5 exhaust would be more than the pumps could handle. What do you think the estimated HP would be?

[cgrey8]

My 89 Ranger came with a single in-tank pump to power the stock 2.9L V6.

If older Rangers had dual pumps, I wasn't aware of that. But I'm not an expert on what the older Rangers had and didn't have as far as fuel pumps.

[Erics88]

Ok. I changed the filter and the checked the fuel bowl in between the two pumps. The filter was a little dirty, but not bad. I put the fuel pressure gauge on it and ran it. Just sitting in the drive and blipping the throttle, the pressure would jump to 36-38psi then drop to 30-31psi the back to 34-36psi. If I ran it at a steady 2000 rpm or above, the pressure would drop to around 29-31psi. Turn the key off, then back on, the pressure would go to around 38-40psi. So, bad pump, or is the motor more than the pump can handle?

[Erics88]

Well, got the truck put back together and took it out for a drive. Knock on wood, it ran great, never stalled or died. I guess that the fuel filter being to close to the left header, and it was dirty enough, was my problem. We'll see. Thanks for all the info and ideas. Hopefully when I talk to you guys next time, it won't be about this subject.

[broncobowsher]

The Explorer based fuel system, was that a return or a non-return system. If you hooked a non-return system to a return style pump you will deadhead the pump. This makes them run hot as ther isn't fuel circulation to cool them off. The factory Explorer non-return fuel system is designed to handle this. I have not opened the Explorer fuel pump but I have delt with a bunch of other brands non-return fuel systems. They run a fixed, non-manifold referenced fuel pressure regulator in the tank.

The early 2-pump systems are not really 2 pumps in series. There are 2 pumps pumping 2 loops of fuel. The low pressure in tank pump lifts fuel and feeds it to the frame rail accumulator that everyone tends to ignore. Excess fuel from the accumulator goes back to the tank. The high pressure pump pulls off the accumulator and returns to the accumulator. The reason for the accumulator is it acts like a carburator float bowl. It keeps the engine supplied with fuel during those brief periods of time the in tank pickup sucks a gulp of air. Later they figured how to keep the fuel pump submerged in fuel inside the tank when running low on gas. This is when they went to a single pump system.

[Erics88]

My Explorer intake was from a 96, and I believe that this was the return style set up. Am I correct? It has two fittings like my ranger and the mustang. I drove the truck again today, and it died. Thankfully I was close to my uncles, so we towed it to his house. Started pulling fuel lines and checking the rear to front fuel pumps. Rear was working and shot fuel when the key was turned on, the front pump didn't. So, I'm going to change it. Broncobowsher, would I need to eliminate the accumulator to run a high pressure pump in the tank? Or you think that I should just replace the in-line pump?