94 lift pump

[ak diesel driver]

My lift pump (new) doesn't seem to put out as much fuel at the filter drain during cranking as it does when I jumper pin g. Any ideas?

 

[chevyinlinesix]

The engine is consuming fuel as it turns over, decreasing the amount available to flow out the filter drain.

 

[ak diesel driver]

Pmd was unplugged

 

[teroma25]

My guess...your current draw is greater while crankin'er over which in turn isn't leavin' full power at LP.

 

[Green Machine]

If its not what chevyinlinesix said (since the PMD was unplugged) I would venture to say teroma is correct. If I would crank my truck with my doors open and the interior lights are on I can see the lights dim when cranking.

 

[ak diesel driver]

Didn't think it would be that bad went from a pretty good stram to just barely trickling.

 

[Green Machine]

Have you tested it just with the engine running?

 

[Pruittx2]

Didn't think it would be that bad went from a pretty good stream to just barely trickling.

Kinda sounds like a prostate problem ):h

 

[jrsavoie]

Kinda sounds like a prostate problem ):h

LOL

 

[ak diesel driver]

Have you tested it just with the engine running?

No I'm waiting on my resistor and opsu from Leroy

 

[JMJNet]

If this is on a 94, you may want to think of adding the LP relay so it does not depend on OPS for electricity anymore.

 

[jrsavoie]

If this is on a 94, you may want to think of adding the LP relay so it does not depend on OPS for electricity anymore.

X 2

 

[ak diesel driver]

It's already on my list.

 

[ak diesel driver]

I was also thinking about a switch on the dash for a lift pump prestart prime.

 

[jrsavoie]

I was also thinking about a switch on the dash for a lift pump prestart prime.

I thought the lift pump did start with key on 96 and later.

I did that on my 89. Also very handy for priming the fuel filter. It might be best to run it with a start button and relay to shut it off after the OPS takes over, thus keeping the safety feature the OPS provides.
I frequently forgot to shut mine off after starting. I had it tied in to key on so it shut off with the truck if I forgot.

 

[ak diesel driver]

I was thinking a momentary switch that I could prime with before I turn the key to the start position.

 

[buddy]

Well, it doesnt matter if the PMD was unplugged. When cranking the IP is still spinning and moving fuel through it, the PMD just isnt opening the metering valve to send to injectors. Still returning fuel to the tank.