2nd Gen Non-Engine/Transmission LP wiring harness question

[easleyj1]

My buddy came to my house yestetrday so i could help him change his FF. Could not get the system to prime, checked his FP with my mechanical gauge and it had zero FP. We were going to install my spare LP when i noticed that instead of a plug for 12V power, he has two wires that appear to be bolted to two terminals on the bottom of the pump. Is this normal on a 1999 model. I thought that all LP were the same 1998. 5-2002?If anyone that has a 99 model they could look at and let me know if it has a plug or not I would apprechate(spl?) it. Thanks.

 

[MBFARMS]

I think that the 98 and 99 had that pigtail setup, but was revised with the newer pumps. If you trace those two terminals it should go to a plug near the block. The new pumps come with an extra length of wire to go from the plug near the block to the newer style plug on the pump.

 

[rweis]

A lot of members use the OEM pigtail to trigger a relay that provides full battery power to the lift pump. If you are that deep into it might be an idea to head off lp electrical problems in the future.



Bob Weis

 

[easleyj1]

Thanks for the suggestion but I don't think he would go for moding anything. I just need to know for sure that a replcment pump is going to have the proper wiring harness adapters to get him in the road. On a side note I am not sure but I think he has toasted the VP. Can Autozone read the codes on our trucks? Thanks



Jonny

 

[Thomas]

The pigtail - Cummins P/N 4025182 - is needed model years 1998 & 1999. For these model years the engine harness is attached to the lift pump lead wires that you mentioned.

In 2000 things changed slightly. The engine harness attached directly to the pump.

The pigtail is just a short extension cord to get from the 1998-1999 engine harness to the 2000-2002 revised pump.

 

[easleyj1]

That's what I needed to know. Thanks.



Jonny

 

[lumberjack98]

is it benificial to run a relay to the lp? does the voltage drop that much?

 

[rweis]

I think the thinking is the lp's are such a PITA that whatever we can do to help them run the best they can is better.



Bob Weis

 

[easleyj1]

I think that the ECM drops voltage to the LP at start up to prevent a hard start condition or so I have been told. Is that correct? I think the next time I am messing around with my fuel system I will hook up the volt meter and see if I can spot this drop. On a side note Bob, could you post the source for the thermal blanket that you used to insulate your VP? thanks.



Jonny