Engine/Transmission (1994 - 1998) fuel pressure readings

[djreed]

I am wondering about the readings I am getting. I was getting 13-15 psi running down the road loaded or unloaded. I was due for an oil change and fuel filter. I use wix filters if you need to know. changed them out pumped up the filter and took it out. I am running 8-10 psi now. Should I be concerned or is the new filter less restrictive. I am going to look into a lift pump soon just for preventative maintenance. Any suggestions where to get one? Thanks. DJ

 

[Matthug]

The overflow valve is a more likely culprit-

http://dodgeram.info/tsb/1996/14-07-96.htm

 

[EKlem]

That definitely sounds too low. Bosch actually publishes a number for the minimum psi that the injection pump should see. Assuming that you have the stock mechanical pump, your pressure readings are lower than what other people seem to experience. Somewhere between 18 and 24psi seems to be standard for these. Matthug has a good suggestion that it might be the overflow valve.

 

[djreed]

What is the overflow valve and where is it located? Still learning.

 

[Matthug]

The link I posted gives that information.

 

[djreed]

Thanks. I found that after I wrote that. Also if it is the overflow, is there a cheaper place than dodge dealer to get one. They are asking $159 for it. Maybe that is what they cost. I hope not.

 

[Joe G.]

ANY after market source is cheaper than Dodge. I got one from TST Products. I think it was about $70 or so. Can't remember for sure.



You can check the OF valve pretty easy. Clamp the return hose with a pair of pliers. If the fuel pressure goes up a lot then the OF valve is bad. If not much affect then start looking for something else.

 

[djreed]

Thanks for the help. I will let you know my results.

 

[WDixon27]

on mine after i got the dead of valve going i found out that the lift pump was crap too, i would get 20 something psi at idle but it would drop instantly with any throttle even in neutral

 

[Matthug]

Well, mine were both taking a dump. First time my pressure was 10 PSI at idle and 18 or so at 2000 RPM. Changed the overflow valve, then had 20 PSI at idle an 25-26 at 2000 RPM no load. Then changed the lift pump, 24 PSI at idle and 34 PSI at 2000 RPM! I have 258K on my truck so the pump was definitely tired, still working but not quite up to proper specs.

 

[djreed]

It soundslike it would probably be a good idea to get a lift pump coming and just replace both of them. I suppose with 210K mine is probably a little tired too. I will check anyway to see what it does by doing the test as told in the link you gave me. Will still let you know, Thanks.

 

[Joe G.]

The lift pump is probably ok. Mine has 242K miles on it. My truck idles at about 28 PSI and runs in the high 30s.

 

[Dave M]

I got my spare overlow vale from Piers Diesel. Here is a link to their price list:



http://www.piersdiesel.com/DodgeUSPrice.htm



The "overflow valve" is $55 and is part number PDR2012050. The "94-98 12v 2nd gen lift pump" is $129 PDR2116316.



They were very knowledage and helpful and will talk about your problem.



I'd try the overflow valve (after testing it with pliers as mentioned) and check prssure before going for the lift pump. Of course you could order one as a spare and get both at once.



Good Luck,

Dave