Well 3 nights ago the truck was running very strong but was low on diesel, so we got some diesel from a different store (the usual hi volume place we go to was closed for some odd reason)


About 3 minutes after leaving the station the truck starts to stumble all over itself. Im like "WTH water in the diesel!!!" Drove back and inquired as to this possibility to the attendant and he went out with the stick and yellow paste to test for water. There was only about 1.5" of water on the bottom of the diesel tank...


Now having recently rectified this trucks lack of power, the exploded vacuum pump, a new vacuum line, a new vacuum solenoid valve, and found the missing short, it's ALMOST running ok....lol


Im going to change the fuel filter, and the OPS and the Lift Pump were JUST changed not 1 year ago, so I'm hoping I just caught a bad batch of diesel. Does the factory fuel filter remove water too? If so I can just add a demulsifier to get any water to drop out of suspension...

No GM filter manager only alarms for presence of water, as for emulsifiers; depends how much water you got in the fuel, with key on and filter bowl drain open I'd pump down the tank some into a bucket or jar and see if a lot of water separates out after sitting a while, I carry a spare can of Diesel in the bed just in case I go somewhere that might not have many high volume Diesel pumps nearby.


Mom & Pop convenience stores that don't sell much Diesel on a regular basis should be avoided for just such a reason, also not a good idea to go less than 1/4 on the tank, GM gages notoriously bad for linearity, that 1st 1/4 goes for 150 mi on my truck, other 3/4 only takes me to 250 or so mi more. Fuel cools the IP and PMD low fuel in the tank elevates it's temp, plus any crud and water resides at the bottom of the tank.


Going low you may have even pulled in water laying in bottom of your own tank. I highly recommend adding a RACOR or similar 10 or 20 micron filter pre lift pump with a AQUA BLOC element to knock out the water, it's detrimental to the lift pump as well, water collects in bottom of the RACOR and can be drained out.Edited by: Turbine Doc

yota,


The supplypump could be intermittent because


of OPS contacts burningout.


Truck idleing, open the bleed on the filter and check for air/fuel pressure.

About 3 minutes after leaving the station the truck starts to stumble all over itself. I'm like "WTH water in the diesel!!!" Drove back and inquired as to this possibility to the attendant and he went out with the stick and yellow paste to test for water. There was only about 1.5" of water on the bottom of the diesel tank...


...





I missed this 1st go round, Who's tank was showing 1.5 " water yours ???, where is the suction of the stores pump, 1.5" of water is free water, what about the emulsified water in suspension above that 1.5" in their tank sounds like you now have some in yours in yours. At a minimum I'd not mess with that fuel dump it, IMO they owe you a tank of good fuel, and also have them sign a piece of paper acknowledging the fact they pumped you bad fuel, may cause problems down the road, GM charges $250-600 to drop & clean a tank over and above whatever that find bad lift or bad IP, maybe have GM test the tank for water content.

QM,


Go back what was last action before the problem, truck was running fine before refueling, got fuel truck started running like crap, water is in stores tank, any is too much IMO, yes it could be OPS/lift pump power, but before going down that road I'd check into fuel quality 1st, too coincidental truck started having problems after taking on fuel. A truck will run without a lift pump, poorly when towing or hard on acceleration, stumbling a normal cruise speed leads me away from lift pump.

Yota,


After changing the filter, you can add fuel to the bowl manually, or easiest way is to key on trans in Drive on your truck IIRC, lift pump will run, run pump with bowl vent on top open until you get fuel out the top, shut off key, that should get most of the air out, enough so that remaining air won't prevent a start.

Water in fuel is easliy verified by drawing off a jar full and looking at it. If it is hazy and hard to see through it's full of water.


Knowing how to check for liftpump/ops operation and verfy supply pressure at the IP is essential to owning this truck.

If you think you have water I would not drive the truck AT ALL because if the water has gotten high enough in the fuel filter to overflow into the injection pump and cause the stumpling you have at lease 1/2 of the fuel filter filled with water.


To test and remove this water open the fuel drain line coming off the bottom of the fuel filter. This hose is to the left of the center of the engine just behind the fan belt and has a little "Tee" handled valve at that location. Open the valve and put the drain hose in a 32 oz. bottle. Put 12 volts to the Gray wire coming off the oil pressure switch to force the fuel pump on and watch the flow into the bottle for water. If only a small amount, a tea spoon, of water comes out there is only a small amount of water in the fuel filter. If a large amount of water comes out or all water comes out you got a real load of water and should consider dropping the tank.


But do not drive the truck untill you are sure the water is no longer coming into the fuel filter.

Wow I wish I had come back and read this before testing out the new down pipe and crossover....http://www.dieselplace.com/forum/smileys/smiley5.gif


I spent all of today swapping out the crossover and downpipe (flowmaster) from summit. When I was done I took a shower then took it for a drive. The truck is running stronger than it ever has and for the short drive (<10min) it never stumbled. I also spanked a ford taurus pretty badly too....http://www.dieselplace.com/forum/smileys/hihi.gif


After reading this post (and wishing I had read it earlier) I'm thinking it could have been something else too...going to check fuel pressure/water/air/fuel filter tomorrow when there is more light.

nothin like beating your first taurushttp://www.dieselplace.com/forum/smileys/smiley20.gif


(u spelled counting wrong in your profile)Edited by: steiner43511

TD - there was 1.5" of water in the filling station's huge tank. The attendant there said that the pumps pull from about 6" off of the bottom of the tank.





I saw a clear plastic bottle about 20 min ago, and I couldn't help myself, I went outside and filled it with some diesel from the truck. No water evident, but a lot of BIG particulate matter. Im letting the bottle sit overnight to see if anything comes out of suspension...


The fuel filter was last changed by dad 6 months ago, so a new one is definately in order. Im left wondering if the attendant took out the filters on his pumps that are actually on the line so that they'd pump faster.....


Lesson learned, hi-volume only....

incidentially I had to fire up the truck to get any diesel to come out of the drain valve....nothing I did would kick on the fuel pump or lift pump without the engine running....is that normal? (I didnt try to short anything out to force the pumps online as I dont exactly know where everything is back there.)


Incidentally nothing came out of suspension from the diesel - it looked as it was supposed to, perfectly clear green.Edited by: Bumpin' Yota

...Put 12 volts to the Gray wire coming off the oil pressure switch to force the fuel pump on and watch the flow into the bottle for water...


Do you have any pics so I know which gray wire to put 12v to? I know the OPS is down there below the filter somewhere but I haven't a clue what is what. Im completely new to diesels if yall cant tell....lol

If you look in behind the OPS you will see a small harness coming of the fire wall leading down to the OPS, whick looks like a 1 in dia. by 4 iin cylinder with a wire connection at the top. Slide back the harness cover and you will see a gray, tan and an orange wire. The may also be a black wire in that harness. Tap into the gray wire and attach that to you battery and the pump will operate.


Check under the fuse block under the hood. If you see a short wire going nowhere that should be a place to supply voltage to the pump also. Not sure the 94s had that wire that is why I suggested the gray wire at the OPS.

Also you can remove the fuel pump relay in the under hood fuse box and jump it under there. Nice and easy and both feet stay on the ground too. Here's a link to some pictures


http://dieselplace.com/forum/forum_posts.asp?TID=16384&K (http://dieselplace.com/forum/forum_posts.asp?TID=16384&KW=bowtie&PN=0&TPN=2) W=bowtie&PN=0&TPN=2


Edited by: bowtie

cool thanks!!


I dont think the '94 has that fuse gang box, but ill double check tomorrow.


Anyhow I never got any water out of the engine, but I did get a LOT of black particulate matter from the drain on the bottom of the bowl. I tried to clean to bottom of the bowl but it was a major PITA to try get the stuff as the bowl is permanently anchored and was much deeper than I thought.


I put the new filter in, then purged the air out, then continually drained the bowl while running until I didnt get any more particulate matter.


No more stumbles thus far, ACs been working great, no dash lighting up like a pinball machine any more, wow this truck is getting back into shape! lol

here is a pic of the black particulate matter. The tiny bubbles you see are actually water that I couldnt get out of the container prior to filling it up with diesel....


would this stuff casue the stumbling?



http://www.dieselplace.com/forum/uploads/BumpinYota/2004-10-29_231330_black_particulate_matter.jpg

It would be interesting to determine what the consistency of those particles is. Perhaps you could strain them out and probe them with a pick to determine if they are metallic or rubber. I've seen many a fuel line deteriorate from the inside out (not specifically on the 6.5). How much material is loaded onto the filter? Enough to cause a pressure drop?


Jim

I didnt see any of these particles on the filter, and now that you mention it, that particulate matter would easily break up. I bet that it is deteriorating fuel lines....http://www.dieselplace.com/forum/smileys/smiley3.gif I'll try to get some more of it and try to strain it out...

Well I shorted out the gray wire coming off of the fuel pump relay with 12v and the lift pump went "ticktickticktick" quickly and filled up the 20oz bottle fairly quickly.


Here is a pic of what I shorted out if anyone ever wonders...lol


http://www.dieselplace.com/forum/uploads/BumpinYota/2004-10-31_141749_PSFuelPumpLowRes.jpg


Only a few TINY little particles...I again looked at the fuel filter and there was no particulate matter discernable....


The truck did have a few minor misses when hot and driving home. Very very minor misses though. Any ideas why?Edited by: Bumpin' Yota

What does your air filter look like? Once it's determined good and it still stumbles unhook the liftpump that's on the framerail under the driver'side door and blow compressed air back into the tank with the cap off, hook that side back up and blow compressed air from the fuel inletline on the injectorpump back through the filter and out the line where it hooks to the liftpump. Then jump the relay's gray wire again with the "T" open till it runs good and clear and then bleed down the filter bleed and see if it stumbles.


the OPS on a "94 is behind the driverside head, right against the firewall. The OPS is the most common reason the liftpump isn't powered, you check it by opening the "T" or filter bleed as you already have with the engine running. You have to have a OPS wrench to remove it easily.