My 1988 F150 2wd, at, ac, ext cab, 5. OL EFI was occassionally not starting, cranking but no fire. Took to shop n they said could not duplicate and banged on bottom of tank and checked other things and I picked it up and paid $100 bucks for nothing. It's been running for about a week, had to bang on tank one other time but then last night got stuck at store. Turned key on and off 7 or 8 times then banged tank and all of the sudden it started after sitting about an hour. Then all today, nothing? The pump primes or I hear it buzz for a few seconds, there is pressure at that bicycle valve on the fuel injection bar when I press the valve stem down.I see the fuel relay switch on left fender next to the airbox under a rectangle cover. Could it be that switch? Do they go out ever and would that be an inexpensive minor mechanical way to start for someone like me who is not a greta mech. Or am I just looking at the replacement of a pump/sending unit? Oh, and the truck has two tanks but the sending unit on back tank has not worked for two years since I bought truck so I always run off front tank; have not touched that switch. I'm a single father working a temp job 25 miles away and have $200 to my name. If I can't fix this myself I'm. Well out of work and soon homeless as I just paid March rent and live week to week with Kids on my temp job. Thank you for your help; ). Desperate dad!
First of all we understand your situation. I can guarantee the whole 2carpros team will make sure we do everything we can to help with this prob. If I understand correctly the only thing you can do that will make it start is bang on the fuel tank. If this is correct then you definately are looking at a failing fuel pump.
Do these relays go bad? Yes two of the relays you see commonly fail. The green one is the fuel pump relay. The brown one is the eec relay[electronic engine control].
But you see we are talking about pumps and pressure. But your post at the beginning said [no spark] so when it would not start did you have spark? And no fuel. Or no fuel no spark? If both this could be the eec relay if only one or the other prob tfi module on distributor. Let me know thanks billymac
March, 6, 2011 AT 3:33 AM
Funny the shop guy said the only thing that came up on the computer check was an eec I think? He said eventually that would need replacing? Could that relay cause it by itself? I told him it had just passed smog 3 weeks ago no problems and he said, Hmmm? He had suggested the banging on the tank thing and I'm not sure if it was that or just waiting for the hour or so yesterday or the 10 or 20 minutes the couple times before or if the banging is what caused it to start? Some guy helping me said try and turn the key on several timeslike 6 or 7 to help prime the pump as sometimes they lack start pressure but that didn't work today, last night though that is what made it start I think cuz it started just after he did that?If it is a relay, either one or both would time help that or waiting, do they cool down or are they pressure sensitive or something? I hear the pump priming or making noise for a few seconds in the tank when I turn on the key.I'm thinking maybe I should at least try to replace those two relays tomorrow as that may be an inexpensive try-to-fix huh? Or at least as a first option? They are only 15 or 20 bucks correct? The spark thing was just me saying that it just turns over with good battery but seems to sound like there is no fuel n just won't ignite or start up, couple times it started and just barely rough idled real low and gas peddle wouldn't help? When it starts it runs great. I tried having someone jump it to see if maybe it needed more cranking amps but that didn't seem to make a difference. Are those relays something I can just pull out and plug new ones in? Thank you sooo much for your help, I am so scared at losing my temp job and have no other ride or friends to take me to work monday so I need to try anything tomorrow I can!
March, 6, 2011 AT 7:31 PM
Yes replace those relays if they did come up on a scan. This means at least one time they have failed. Yes just unplug them plug the new ones in. If either one of these fails it will not start. If it were mine I would replace them. So atleast you know it is not them.
If not them then the fuel pump is going to be the prob. You see what is confusing about the pump is that it intermittantly runs. But the pump is just a very small motor this motor has an armature just like any elec motor these armatures get flat spots on them. So it depends if when the motor shuts off where it stops if it stops on a flat spot it will not pump no start. Cycleing the key and beating on the tank will normally jar motor off flat spot and start pumping.
Cycleing the switch makes it hard to tell if you are actually bumping the pump motor or if you are bumping the two relays.
If it won't start and you do not hear the pump but hear the relays then beat on the tank vigorously and see if you can kick pump on.
Some of these years had a pump mounted right under the driver on the frame. Not sure if yours does. This was a high pressure pump the pump in the tank would pump fuel to the hp pump then to the injectors. When these pumps failed you would have idle no accell.
March, 12, 2011 AT 10:51 PM
Well. It ran ok for about 5 days after fuel relay replacement. Now back to not starting so I guess I'm facing a pump replacement now? Where can I buy this pump/sending unit inexpensive? How much would it cost to have put in or could I undertake this as an amature mechanic? Is the high pressure pump on frame under drivers door possibley the problem as its way easier to replace; )
March, 13, 2011 AT 3:33 AM
So replaced the relay switch and it started fine for a week. Now back to occasionally starting and the banging does help but today. No start again ; (. So, it has dual tanks, I dont use rear tank as it the sending unit has never worked so always ran off front tank. My question is do both tanks have combo sending/pump units and is the unit under the drivers door that has 4 lines coming into it a high pressure pump and not a fuel filter? Could it be the high pressure pump? Or am I facing dropping the tank and pulling the sending unit/pump as an amature as I do not have money to pay a shop to do it; (. Is it possible as an amature mechanic? Meaning I use to do tune ups, replace starters etc on my old non smog cars/boats in the 80's. Checked the distributor cap and it looks ok also. Hmmm. Please help!If it is the pump where can I buy one cheap!
March, 13, 2011 AT 8:19 PM
The unit under the friver with 4 lines is a filter. Not a pump you have a pump in each tank. Yes you have to drop the tank and replace it. Not as bad as it sounds good luck
March, 13, 2011 AT 11:16 PM
Any suggestions on where to order it from? Dealer wants $330. What online part sites you recommend?
March, 14, 2011 AT 10:26 PM
NOT SURE IF YOU GOT LAST REPLY BUT I SENT PRICES AND PART NUMBERS YOU ONLY HAVE TO BUY PUMP NOT SENDER.
March, 15, 2011 AT 12:20 AM
I didn't see prices and part numbers? And the sending unit has not been working correctly anyway so I was assuming I should replace both at the same time? Thank you. Was there an attachment I missed or something?
March, 15, 2011 AT 8:30 PM
WELL YOU CAN REPLACE BOTH BUT IF FUEL GUAGE IS WORKING YOU ONLY HAVE TO REPLACE THE PUMP. PUMPS ARE AROUND 60.00 SO UP TO YOU WHICH ONE YOU PREFER TO CHANGE. THANKS FOR WRITING