Got the new computer installed after I checked the power and grounds on the connector to make sure I didnt have any shorts or bad grounds. Turned the key, and it starts right up and the check engine light goes out, also the fuel pump runs for the initinal 2 seconds like it should, before it would run all the time.. I let it run for a while then I shut it off and see if I can check for codes. I hooked up the jumper and it flashes an 11 (system pass). So he did have a bad computer. I decide to test drive it and I got 1 block before it died. Towed/pushed it home and I began diagnosis and it turns out the fuel pump quit. I turn the key and I dont hear the pump but I hear the relay click. I take a 10 minute break and when I get back it starts up? I had to go to work so I quit untill that night. I get home and it starts right up so I sit there and let it run and I shut it off and restart it and I hear the fuel pump run for two seconds every time I turn the key but after a few minutes The fuel pump starts sounding different like it lugging and then it just quits turning on so I grab my meter and I test the connector at the inertia switch and I get 12v for the two seconds then it drops to 7v. To me that sound like the relays working but the pumps quit. He said he replaced the pump but he just replaced the pump and not the assembly. He also used to have the pump wired up to a toggle switch. I think the pump is quitting when it gets warm or there is some bad wiring. I heard pulling the bed is easier then dropping the tank so I'm going to pull the bed and test the pump there. He didnt do any of this work himself he had other mechanics do it. I hate fixing other peoples mistakes.

 

It might be a clogged fuel sock in the gas tank. A new sock costs under 10. The problem is dropping the tank or taking the bed off to get the pump/sender out of the tank to replace the sock.

 

I was thinking that too. He said that it only cost him $40 for a new pump and the ones I'm looking at cost $90-120 some include the sock and some dont. I doubt that the other mechanic replaced the sock judgeing by his other work. I'm going to pull the bed tomorrow and take a look.

 

to access pump I use to remove a bed.... I advie you to check all connectors when sender will be removed from tank.

BTW, when you have the good PCM it is a time to fix old one... LOL and sell it to someone ore use like spare one. I have one no-immo Mercedes PLD ECM to use it like spare one, but I have a collection of Flash and EEPROM dumps and I soldered in board connectors instead of memory chips and I use to swap chip on demand (for Mercedes, Mitsubisi, Volganin, Freighliner appl, for OM904,906,501,502,460,457 enginel)...

So no reason to trash old PCM

 

If you can, you should put an ammeter in series to see how many amps the current pump is drawing. I think you'll find that the amperage goes up after a few seconds. A common thing that happens is that as fuel pumps age, they start to draw more amps. The "mechanic" may have installed a used pump, or it may be the sock plugging up, or it could be the wrong pump. You can get a new pump for less than $50 or a complete sending unit for about $200, depending on model and year.
tom

 

I got the bed off today it took less then an hour, way easier then dropping the tank. Started checking things out and I found that I'm getting 12v to the pump for two seconds when the key is turned and 10-12v while cranking, I grounded the fuel pump test terminal to the neg batt post and got 12v all the time with the key on. So it looks like the wiring is good. The pump ran for a while (when it wanted too) when I was doing the test's and now it's dead, I even put 12v directly to it from a battery and nothing. I'm going to autozone tomorrow and I'm going to get a airtex complete fuel pump assembly (strainer,pump,sender) and a fuel filter. They want $97 for just the pump and $100 for the complete assembly(strainer,pump,sender) so I'm getting the complete assembly.

 

Yah think you can afford the extry $3???? A pump for my Sable was about $50, but the problem was the sender was hokey, messing up the fuel gauge. The Bosswife said: No! Fix the gauge! So, spent the extra $150 to get a gauge working. The pump itself was fine..

Never mind...

Forgot to mention that the 'sender' was about $200 vs $50 for a pump.

tom

 

Went down today and got the new pump/assembly and a filter. I made the guy spring the extra $3 bucks. It was about $120 out the door with a 1 year warrenty. I work all weekend so I will be putting this in monday and hopefully its the last problem, and I can give this guy his truck back. I will keep everyone posted.

 

well, gentelmen, the good idea to pull fuel sender and inspect, then to inspect wiring and to check fuel pressure... but not only bad fuel pump makes fuel pressure drop down.... are U sure FPR is ok?

 

I havent checked the FPR yet, I'm just trying to get the fuel pump working.

 

I have seen this before sometimes pump will run sometimes not sometimes you can bump the bottom of the tank with a mallet (hammer) or fist and they will run. I had a pump less then six months old do this exact same thing run when it wanted to. Replaced that pump again and have no issues since. The bad one was a fairly expensive one form O'reilly the next one was an online purcahse aixtex. Who knows I think they are all made in Chinnia anymore.

 

Its fixed. The mechanic who installed the other fuel pump damaged the assembley and left out some parts. It runs and drives great now. Thank You everyone for all your help.

 

))) have a good ride!!