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Lift pump, relay or OPS? Intermittent fun...

WarWagon

WarWagon

Well it hits on 7 of 8...
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Ok, here is a fun intermittent one. Lift pump, relay, or OPS? It would be easy if the failing part stayed 'dead' and didn't come back to life after starving/stalling the engine for fuel. :mad2:

I have a OPS relay bypass wired on my 1995. This has the OPS powering a relay that powers a 4 Amp Mallory lift pump. I lost power twice traced to the lift pump not running. I caught the lift pump in the act once not running. I was able to jump the factory lift pump relay (this is not the bypass OPS relay) after the engine stalled out and the lift pump started running. Then the entire system continued to work normally.

Powering the bypass relay appears to work and start the pump every time.

So are the brushes in the Mallory about to fail? Is the OPS going intermittent or is the relay the OPS powers going out?

I replaced the relay, but, as it was cheap and easy to get to it is not likely the problem... :rolleyes5:
 
Put 12v to Mallory relay this will elminate the ops and tell u if u need to focus on relay and lift pump or ops but bypass ops before u go to trouble of pulling center head and replacing ops unless u have ops ext hose and the ext hoses just present more places for a oil leak so I stay away from them

Sent from my SAMSUNG-SGH-I437P using Tapatalk
 
I have went as far as put clip leads on my fluke meter hook to where your 12v goes Into your lift pump put fluke in cab so u can watch for voltage failures

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If u see voltage failures at pump move clips to relay if u see voltage failures there keep moving toward ops till u find where the problem is

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If u find ur Mallory has failed please post its service life I have used holley blue lift pumps on lp&filter upgrades on warwagons before and service life is not what I expected never tryed a Mallory but would like to know service life on them am looking at walbro for my 6.5 upgrades but im still in planning stage

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Looks like I should pull the motor and check/replace the brushes. $20.00 brush kit. I would be running a Walbro now if it wasn't killed by bad fuel. The lower pressure Walbro pump is running after a rebuild from the same bad fuel. This pump is overkill, but, quiet vs. the Holley or carter vane/roller pumps. Bout 30K and 2-3 years on the Mallory. Used the Comp 140 Alcohol/Methanol Application due to biodiesel B99 use. The first one was replaced under warranty for a seal leak in like 6 months. Overkill for the job. It is my second choice due to cost alone. The fuel pressure gauge doesn't move from 15 PSI at full engine RPM.

http://sonic.net/~mikebr/efi/problems/fuelpump.html
 
Was the walbro on bio just wondering what u are calling bad fuel I see u are from az have u been getting fuel at speedies truck stop on I 40 near the az/nm state line

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Sure enough as the site above has - the brushes in the pump were worn out.
 
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