Fuel in electronic connector?

[RCourtney]

I'm working on my first lift pump replacement, trying to resolve my DTC 35 stall/restart problems. When I separated the electrical connector, diesel fuel started dripping out, and kept dripping! This was before I loosened up the nuts on either end of the pump, and there was no evidence of leakage anywhere else in the area. Anyone else seen this before? Is there a logical explanation? In case it matters, I just had my fuel filter replaced by the local oil change place, and the truck won't start now (no fuel out the air vent when cranking).

[Barry Nave]

Bad lift pump for sure
With out lift pump you will not be able to prime the new filter of air.
probley the oil change guys did not prime the filter. Did the truck run after the filter change? or was you stuck in there lot?
On my 95 after a filter change,I can put truck into drive and turn key to start to run LP to bleed air and fill filter bowl.
Unpluging the elect. to the LP should not have fuel coming out,though the LP could still work.

[gmctd]

Failing seals in lift pump can allow fuel into electronic driver area, which then trickles out thru wiring harness, into connector.

Excellent indicative of lp replacement time.

[RCourtney]

Bnave/JD - you were both right, of course. I actually heard the pump running for the first time! I think the oil change guys got it started by adding fuel (diesel, hopefully) to the filter holder. It actually started again when I left work that day, but not the next day. After changing the pump, I bled the air out like you're supposed to (lots of fuel came out of the vent). I thought I was all set, but now more problems. On my first short test drive, the engine stalled twice (same as it's been doing for a couple of weeks), but it seemed to take longer to get it started. I made it home and it's been sitting for a couple of hours and I can't get it to start for anything! Any ideas? I don't hear the pump any more. How often should I hear it? Maybe I have an air lock?

[tom.mcinerney]

Rob--it doesn't hurt to replace the OPS at same time as LP...they can wear out together. If/when you get engine started, check for power at LP (if power, maybe OPS ok, if not, need renew.

A better fix includes a relay in the line to preserve LP; or John Kennedy's kit.

Of course, there may be other gremlins --from tale of stalling. Not to lead on a goose chase, but old hoses can crack allowing air in lines, the fuel cannister can leak, too. A test for air in fuel lines--insert transparent section tubing at Fuel Injection Pump input, or even return, as bubbles can confuse optical sensor. No bubbles, + ample pressure(4-8psi) at drain valve, fuel OK.

Now can do electrical connection checks. Keep in mind that your ignition switch feeds LP as well as PCM & FSD; replacing switch increases their chance good supply volts.

But really should check for codes each step of way.

[RCourtney]

Thanks, Tom - Does the instrument panel gauge give any indication of the sensor's functionality? It's reading about 45 (psi?)? I'll check for air in the system - seems likely since the fuel filter was changed when the pump was bad. I'm also wondering if the FSD is malfunctioning, since it looks like it's been undercooled for several months. I replaced the ignition switch a couple of months ago, but I'll double-check the rest of the electrical as is recommended.

[ttpost]

as far as oil change places changing your fuel filter i wouldnt trust them, every time i have gone to one of those places they miss grease zerks, or something else. are you sure they put the filter in facing front??

every time i change filters there is alot of sediment in the bottom of the housing which gets stirred up. i always vacuum mine out with a small hose taped to a shop vac. i really doubt that they properly clean the housing.

i dont trust minimum wage guys working on my truck. :eek:

[charliepeterson]

Last spring I had the dreaded stall with a long crank to get it running with a stall shortly after. I just replaced my lift pump a few months before.
The problem was a bad lift pump. I replaced both the OPS and lift pump again and have had no issues.
My stall was more like running out of fuel though. Not like someone turned the key off. That's different.

[RCourtney]

ttpost - yeah, I was nervous about the oil guys working on the fuel filter - I should have watched them closer. I'll check the installation, too, if you think that's a potential problem. The truck did start late last night after it sat and cooled off for several hours. I didn't dare go anywhere, though. I can't get back to it until tomorrow. In the mean time, could someone answer my unanswered questions? 1) Does the fuel pump run continuously (how often should I hear it)? and 2) Does the IP OP gauge indicate whether the sensor is any good? As stated, I'm a Newbie, so I don't know this stuff...

[tom.mcinerney]

The Instrument Panel oil pressure gage is somewhat independent of the OPS: the OPS is one module with two functions, 1.) control LP on/off when Ig Sw on; 2.) feed pressure sensor output to IP gage . The aspect which controls the LP is a set of points (generally considered undersized) which are liable to burn/fry/pitting, especially when the oil pressure gets low at hot idle, and the points vibrate open/closed while switching the inductive load comprised by the LP.

When the ignition switch is in 'Crank' position, the OPS doesn't control the LP. At that time, the Ig Sw energizes the LP relay.

Above description believed accurate for model year '95; later vintage controlled otherwise by PCM + relay....

OPS control of LP used to prevent electric pump feeding fire in events like crash/overheat, etc.
When oil cool, press high, LP can be heard running on after switch Ig off for a few seconds.

[RCourtney]

Tom - thanks, now I know why I've heard the LP running a couple of times after the engine shut off (cold, as you said). I can't change out the OPS until the weekend. Can anyone describe where the fuel pump relay is located? Also, one update - engine has started cold a couple of times but stalled after idling for about 5 minutes.

[Barry Nave]

Rob
Not sure if your running a FSD cooler or still have the PMD system. Our IP is able to lift fuel with out LP once running. A bad LP with a PMD,Stock set up can cause the IP to get hotter when the LP is not working taking the PMD/FSD with it. LP fuel flow on the PMD set up is a must to help the FSD stay cooler as does keeping the fuel tank full.
Changing the filter is not a pull out and drop new in way of changing.
This could and will cause IP trouble along with Injector cloging if any dirt washed of the filter when removing and was left to set at the bottom of the bowl. Ever check to see if your screen is still intacked in the center riser of the filter housing?
I have installed the oil By-pass and now thinking about a prefuel filter.
I Plan on keeping this truck for a long time.
Has any one install a stock filter set up as a 2nd filter?

[tom.mcinerney]

I did. It's nice with the second water sensor--try Peninsular Engines or Avant Salvage if you need another filter housing.

Suggest read other posts on secondary filters, see DMax forum, and also posts by RJWest, tbogemirep, and Damork, try searching.

Here to start:
<http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=004289>

[RCourtney]

Well, I finally changed out the OPS. Also, checked the install of the fuel filter and it looked OK. I didn't see or feel any kind of a screen in the center riser of the housing, though. Can someone tell me how and where exactly to find it? I don't see any pictures in my Helms manuals. Truck still stalls after running a few minutes and is very difficult to restart, then stalls again shortly thereafter. Gonna look for air bubbles next, then replace PMD?

[tom.mcinerney]

Rob-

If, after draining fuel from, and removing filter element from the fuel conditioner/filter assembly, take a look down inside the filter housing. There are two, coaxial (one inside the other) stainless steel tubes on center in housing. Both have thin walls, the taller is central/thinner one, maybe 1/8" less OD than outer, shorter, thicker one. A cylindrical nylon filter screen (with slightly larger diameter base than top) slides snugly over the OD of the taller thinner tube, and seats against the top of the larger, shorter tube.

This appears as a ring of yellow/brown nylon around the taller tube, maybe down 3/4" from its top. The fuel should flow thru screen, the lip/boss of screen seals against inner surface of filter element. Sometimes these screens clog a bit. Sometimes the screens pull out of position when the filter element is withdrawn. One member reported a new filter element wouldn't seat in housing because it apparently came with a screen in it, which sat on existing screen in housing??.

If the screen is missing(or clogged) a replacement may be obtained from your local Stanadyne rebuilder/dealer; TDP Advertiser Gomer's/US Diesel shipped me one long before my local Stanadyne shop obtained one.

Not to be lugubrious (?), but if you've been running without a screen fitted, consider removing the FIP inlet hose barb. This piece incorporates {another} filter screen (stainless steel), a "last line of defense" [quote fr member 'ucaldavis'] for the Fuel Injection Pump.
My fuel conditioner contained a sad looking old cylindrical filter screen....my FIP inlet barb screen contained perhaps 50 'sand' grains(.008"/.015" extent) and other debris which the {SOLE OEM} filter element should have readily trapped.

[RCourtney]

OK, I think I can close this one up. After investigating everything else, I finally bought a remote FSD kit from Bill Heath and installed it. Seems to have done the trick!