I have a problem with my 85 f150 efi 5.0. I am not able to get electrical voltage to the pump or purge pumps. I have checked what seems to be a hundred things and still no answer, HELP PLEASE

 

Is one of the hundred things the inertia switch at the pass side kick panel or the relay for the fuel pump?

 

So you want us to guess what those hundred things were? You have to tell us exactly what you've already checked, and exactly what you found for each one. Otherwise, we'll be going back over the same ground for no reason.

There are no purge pumps. There's a low-pressure pump in each tank, and a high-pressure pump on the frame rail. Some early EFIs use an electrically-operated select valve, but most use a pressure-operated valve with a reservoir. Which does your truck have? Pics would be very helpful.

 

Two years ago it started shutting off intermittently and would not restart sometimes for a day or so , at that time I had installed a new engine 5.0 H.O. I knew that I needed a mass air conversion, so I just parked it untill I had time to install one. I couldnt get it to start at all for this time frame. Last week I installed the mass air conversion m-9000T51 aod version. the truck started and quit. I removed the eec4 and replaced with another one, no change that is when I started. I started by removing the bed and removing the float assemblies from each tank. I replaced the hose on each one then I turned on the ignition, checking both for float variation with the gas guage also both pumped gas as I switched the selector for front and rear. Then I tried to start the engine, it ran for maybe a minute then shut off, as i began to search I noticed that the fuel pump on the frame would only run for maybe ten seconds and quit. I then checked and found no fuel pressure on the rails at all. After removing the inertia <emergency> switch and jumping a wire through the circuit I was able only to get power for about two seconds. I then checked the fuel relay it has constant power and makes a relay click I replaced it any way, no change. I went to the high pressure pump , no power at all. I was working a few minutes before but now nothing. I have checked the TPS <.97ohm> . I then disconnected the plug form the frame pump and wired it directly it will pump and put pressure on the rails and the truck will start, but I cant get any voltage to the wiring at the frame pump and now I cant any voltage at the tank assemblies. I went on and removed the selector switch inside the cab <mounted on the a.c. assembly> and checked it , it has no power going to it either. I have looked for a blown fuse , nothing. I have been looking for a chaffed wire and cant find anything. I also made sure that the harness is grounded by the battery. I found the ignition switch bad so I replaced it also. I replaced the tpi on the distributor ,no changes.I also unplugged the air valves on the fender well and cleaned them. This has baffled me, I appreciate some direction. I can get some pictures. I have owned this truck since april of 1985 so I know all of its history.

 

This is what I meant - we'd have been wasting time describing a STOCK engine, and yours apparently isn't. Yes, post pics. This site makes it easy.

So it began stalling BEFORE the new engine, or after???

Why did you "need" a mass air conversion? What does m-9000t51 mean? Is that some aftermarket kit? What EEC-IV did you remove? Did this MAF kit come with a Ford EEC-IV computer?

How many fuel pumps have you found (total, in & out of the tanks), and what kind of valve switches the tanks: a small electric valve, or a large plastic reservoir with no wiring?

The pump(s) shouldn't run for 10 sec; it should run for maybe 1~2 until the engine spins, and then it should run continuously until the engine stops spinning. Have you pulled the cover off the EECs and looked inside? Do they stink?

There are fusible link wires in the engine & dash harnesses that might have burned out. It's a nightmare to find them, but it's fairly easy to overlay a new wire with a fuse near the starter relay. Read this caption and the NEXT few to get rid of those old relays & swap to the newer style:



There are lots of harness ground terminals, and any of them could be loose/corroded/broken. Look inside both kick panels, and all around the engine bay.

Do you have wiring diagrams for the truck? If not, try to find a REALLY old edition of the Haynes manual:

 

Yes it started stalling after the engine swap, but I assumed the stalling was from the H.O. engine because the firing order changes and the cam in the HO is a roller therefore the vacumn on the air horn changes and a speed density system will no longer be able to keep the engine idling, that is why I changed it over to a mass airflow with a 5.0 HO eecIv system (m-9000-t51 :Fords SVO conversion kit for this swap www.dunnerite.com is where I found one). The kit comes with EECIV computer,MAF, Conversion air hoses, and a new wiring harness for the injectors to adapt the proper firing order. I have a total of three fuel pumps one on the frame and one in each tank. Also a tank selector switch in the cab on the AC control and an electric mechanism under the truck on the driver side frame righ at the back of the cab with all four fuel hoses attached to it .I have not pulled the cover off of the EECs but I have smelled them and they dont smell fried. I have been checking the fusible links.... nothing yet. I have also been checking every ground I can find, cleaning, repairing-replacing. I appreciate the caption it tells me what color the fuel connections are and the EEC colors are.I have been looking for a good manual the new ones do not tell wire color definitions or terminal definitions.

 

No, the engines were MAP/SD even after the firing order changed. And the injector wiring didn't change for the firing order (the injectors are wired into the same banks for both); it changed from bank-fire under MAP/SD to sequential under MAF. There should be 6 fuel lines (2 each for 2 tanks & the engine) at the selector valve, regardless of electric or pressure operation. Search eBay, Half.com, & your local libraries for an older edition of Haynes.

If jumpering power to the tank select switch makes everything work, then just overlay a new wire from a new fuse at the starter relay to the switch. It's not worth the effort to find the fusible links embedded in the harness.

 

Hey, found the problem.... had a broken wire between the FRP and the inertia switch. I must have pinched it during the engine swap a few years ago. Cranked it and it runs like a champ, just needs to run some sea foam and a couple tanks of gas through the old girl. I really appreciate your advice on the truck. Thanks