Having issues with fuel delivery on 88 F150 4.9 six with dual tanks. Too many oddities to even begin to list and now only runs for 5 seconds once a day and only on one tank, so a little hard to diagnose. Gauges don't work either and two new tank pumps installed. The only thing I know for sure is that I put gas in both tanks.

Read that Fuel Selector (not switch) mounted on frame is responsible for switching both the fuel and gauge signal? Is that correct? I was hoping to remove the Selector and then find a convenient place to power each tank pump individually with 12v and hopefully see a puddle from each and then proceed forward. Anyone ever try that?

Also, looking on autozone for a Fuel Selector, I see two models, one with and one without fuel return lines for this model, but both listed as 6 port (pictures show 3). Which one does it need?

6 port motor driven; use when return lines are required; O.E.M. #12336291, U7001
or

6 port motor driven; Use when return lines are not required; O.E.M. #12336290, U7000

Thanks

 

Ok, a couple of things. First off, it shouldn't be TOO hard to track down exactly what your problem is. Here's sort of what I would try (and recently did try on an 88 F250).

First off, and most important of all, pull the codes from your computer. If you don't know how to do this, go to www.fordfuelinjection.com and see how. This will tell you a lot about what is and isn't working on your ride.

Next, spray some starter fluid into the throttle body and try to start the truck. If it starts up (and then dies with a few seconds) then we know that the ignition system is ok. If it doesn't start up with starter fluid, then you'll need to diagnose the ingition system.

If the truck starts and dies, then you need to check the fuel pressure at the rail. There is a little Shraeder valve (like the air vavle on a tire) on the driver's side of the intake manifold. You really need to check the pressure here. You should get like 32-40 psi when the truck is idling, or right after you turn the key to on and wait a few seconds. If there is a problem here, then your regulator could be bad, or someting else in the system could be bad.

If you don't want ot do any of those, then you can do some other little tricks. If you suspect that the problem is the selector valve/reservoir on the rail, you can check this pretty easily. Disconnect the output of the selector assembly (the line going to the high pressure fuel pump on the frame). Don't forget to relieve the system pressure first. Put that line in a gas can (a big one). Jumper the fuel pumps on with the self-tester connection in the engine compartment (do a search here for the diagram, or ask someone to post it) and turn the key to on. Now there should be gas pumping through the selector into the gas can. Toggle the selector SWITCH in the compartment to see if both tank (i.e. both positions of the valve) are working. Assuming you have power to both intank pumps, and both intank pumps are good, this procedure will verify that your selector is working properly.

If your selector is working, then you can move on to check the high pressure pump. You can disconnect the output of the high pressure pump and then jumper the pumps on to see if everything there is working properly.

But, by checking the codes first, and then checking to make sure that you have good ignition, you can save alot of time and effort. Yes, the selector valves do tend to go bad. Mine is bad right now. But, they cost alot (in my opinion) and some other issues could be at play and should be ruled out first to save you time and money.

As far as replacment of the reservoir goes, I have read here that the aftermarket ones won't work, as none of them have reservoirs. Our trucks need the reservoirs (for hills or high loads), and so we must go to the dealer to get a new one ($145-$150) or a bone yard (if you van find one).

Let us know what you find.

 

No, the gauge is switched by the dash switch.They already are, the dash switch switches the power to each tank pump.

As dagray3 said these will not work for your truck, these are for the 460 engine and diesel trucks.
Your selector valve on the frame is non-electrical.

 

All these valves have Ford ID numbers on them.

There are two possibles that fit the application: 1988 F150 300-6:

Marked: E7TB-9F271-AA = Actual Ford part number: E7TZ-9189-A .. Fuel Selector Valve

or

Marked: E9TB-9F271-AA = Actual Ford part number: E9TZ-9189-A .. Fuel Selector Valve.

Both have 6 ports. Neither are for a 351W or a 460.

 

is your pump on the frame working?? i just went through about the same thing and i remember when the pump on the frame rail wasnt working it would fire up for just a few seconds and then quit.

so i would check that first, make sure all your pumps are working,when i have mine running i cant hear the tank pump for the one on the frame its much louder. i unpluged the pump on the frame then you can listen for the ones in the tanks.

 

Ran codes, got a "Fuel Pump secondary circuit failure" which I suspected since I do know that the rear tank appeard to stop working again while test driving a few days before it all stopped working. Just had both tanks pumps replaced 30 miles back and one had to be replaced twice while it was being repaired. Not a pretty story, lots of frustration there. Thus the reason I am delving into this one myself this time.

I am assuming "secondary" means rear tank or is that the main pump being called secondary.

True to form, the truck started right up and ran for about 5 seconds and then shut down. Went and bought starting fluid. When I returned it started and ran for about 2 seconds and then shut down. Each spritz of fluid into the intake with hoses disconneted allows it to start and run for a few seconds. So I'm still thinking ignition is good and fuel delivery is the issue.

The pump on the frame growls a bit more than I would like to hear when the key is turned so I have my doubts there too. Also replaced the fuel relay just to be sure it wasn't cutting out.

Thanks for the infor and part numbers on the selectors.

Yes I had my doubts the selector also controlled the gauges since the tank switch is a DPDT.

Fuel pump self tester jumper sounds handy, I will search but if anyone has a link that would be appreicated.

 

There is a fuel strainer screen in the input side of the fuel pressure regulator and if there were a blockage there your engine would act like this.

To run the fuel pumps with the engine off just ground pin #6 of DLC/VIP test connector and turn on the key.







/

 

A few things can set this code.
1. If you ground pin #6 of the DLC and run the fuel pumps.
2. A bad pump motor drawing the voltage down (any of the three pumps).
3. A fuel pump relay not responding to a command from the EEC Computer.

 

yeah, it sounds very likely that oyu aren't getting fuel to the engine. It can be tricky to work out exactly what the problem is though. I would say now would be a good time to go ahead and see if you are getting fuel to and from the reservoir. You should be able to tell from that whether or not your intank pumps a re still good, and whether or not your reservoir is good.

keep us posted.

 

i just went through all of this sounds just like what mine was doing i replaced the tank pump and the frame pump. and both went bad again my tanks had some very very fine crud in them. i took the rear off for good and put a new tank on the front and replaced both pumps again and its not given any trouble since. so if your tanks are dirty you are wasting money on new pumps till you get them clean or replaced. trust me i learned the hard way when i had to throw a brand new pump away because the tank was dirty. luckly napa replaced the frame pump free of charge.

and like i said before, when my frame pump was bad the truck would fire up for just a few seconds and then quit just like yours is doing.

unplug your frame pump hoses and the elec plug and see if your tank pumps are pushing gas to that pump. if so then that will tell you your problem is from there on forward.

 

Better late then never, the problem is solved. Obviously I was not in a rush. Both tank pumps had gone bad. The non-powered fuel selector on the frame works by diaphram action based on which pump is pushing fuel. It then shuts off the other lines so fuel doesn't flow back into the other tank. I confirmed this by blowing into the inlets and hearing the diaphram close on the other inlet/outlet combo. Anyway, you DO NOT disassemble this item as there is no filter in it. It simply has a fuel resivoir. Well, best I could tell, the fuel from the tank was siphoning very slowly into this switch resivoir. Once it was full, the engine could be started and would run until the resivoir was empty. This fully explained the length of run time vs the time it sat. Also, the fuel selector valve was indeed faulty. So.... After dropping the tank and finding rust and substantial rust on the new pump, I replaced the tank, pump, fuel selector valve and poof, like magic, it sprang to life. Of course everthing else is falling apart now... left the muffler in the road today. At least I know what's wrong with that.

 

Subford help out please

No power to hi press pump

Pin 60 eec good its ground pin 40 same
Pin 22 ing hot good
No power to pin 57
37 has power

Domt use rear tank shows full
Front 3/4

Switch on front ing on red no power blue has power yellow/white has power brown/white ground yellow/white and red/yellow continuity between the two

Switch to rear
Yellow/white yes power yellow/blue yes power
blue/yellow ground with yellow/blue and yellow white
Yellow/white ground with red/yellow and red and brown/white

 

If 37 has power and 57 does not then you have a problem in the EEC Computer plug itself.

 

So is there a way for me to fix that? Like an new plug aftermarket plug from somewhere? Or would that be an eec problem itself

 

It would have nothing to do with the computer (not getting power to pin #57).
Take the back off the computer plug and check between 37 & 57 with an ohm meter.
It should be a dead short between them.