Help :)... I have (2) questions. Engine cut-out and contaminated fuel filter bowl

[ccole]

Hello all and Happy Holidays!
I have 2 questions for the 6.5 guru's and truly appreciated any input.

1st. On my 1995 6.5 Chevy (115,000 miles), the engine will every now and then cut-out or miss for a very short, split second when driving between 50 - 65 mph. Any speed above or below this, it drives fine. It also runs/starts great at all other times. The gauges do not shut off or anything thing like that. Its simply one short, but harsh jerk. So, my thinking is that it was fuel related (and per suggestions from a previous post.) Thus far, I have put in new injectors, new transfer pump and also temporaily bypassed the transfer pump so that is live whenever the keyswitch is on (for testing purposes). It also doesnt seem to be related to temprature of the engine, so hopefully that rules out the PMD (which is still OEM mounted in the intake of the engine). Anywho, after these updates..... the truck still does have the problem. My question is, do you feel the PMD could be causing this, even though the problem seems to happen even when the engine is cold or hot? Or, dieselpage Moderator JohnC also mentioned possibly the transmission torque converter clutch disengaging for a split second at highway speeds. Anybody else heard of this happening? One thing to note, the auto transmission does shift into 4th gear (overdrive) very harsh. Reminds me of the powershift transmission on the Deere 4020's shifting from 7th to 8th :)

Okay, question #2. Same truck.... After putting on the new lift pump, I thought it would be a good idea to also replace the fuel filter. I pulled out the old cartridge filter, and saw all kinda of shiny little metalic flakes in the filter bowl housing. :( Not good! I tried a magnet pointer, but it wouldnt attract to the foriegn material. I would assume it is some sort of aluminum alloy.?.?. So, I got a suction gun and sucked all the fuel out of the bowl housing and used clean paper towels, fast evaporating brake cleaner and an airgun to cleaner the bowl out. Once I felt it was about as good as it can get, I put in the new filter. It seems to run fine, but where in the world did these metallic flakes come from?

Again, I truly appreciate any input on either of the 2 issues. Thanks in advance and Merry Christmas!

[atom_c]

You might want to go to heathdiesel.com and click on his HDP Blog link. Scroll down till you get to the "Fishbite" description for 94 and 95 trucks. I have yet to make the repair Bill Heath describes on my 95, but I too have an occasional seemingly random miss at highway speeds. Good Luck!

Adam

[mobilevet]

ccole - I have a 1994 Sub with the 6.5 and seem to be experiancing the same thing you are. At interstate speeds (70 mph) occasionally you'll get a "miss" (I describe it this way because it feels like a gasoline engine that is missing). Usually it only happens once and then you are good for many more miles before it happens again. Sometimes it is mild/gentle - sometimes it is very abrupt/rough. Yesterday it happened (a rough one) and for the first time the "service engine soon" light came on and there was an associated power loss. None of the gauges showed a problem (normal op temp, normal oil pressure, etc) so I drove it on home about 30 miles. I'm going to change the fuel filter in the next few days (hopefully) and see what its condition is. I hope it is the cause of the power loss?? We'll see.

Ps - is there anyway to check this "service engine soon" light without taking it in? Surely there is a code list somewhere out there....

[ccole]

You might want to go to heathdiesel.com and click on his HDP Blog link. Scroll down till you get to the "Fishbite" description for 94 and 95 trucks. I have yet to make the repair Bill Heath describes on my 95, but I too have an occasional seemingly random miss at highway speeds. Good Luck!

Adam

Thank you for the replies. Also, thanks member "atom_c" regarding the suggestion on reading Heath Diesels blog on the "Fishbite" theory. This sounds exactly like my situation and also seems like the similar problem for member "dieselvet". The $58.00 part to correct this problem is a heck of alot better than a new IP or a torque converter clutch replacement. I will definately order one of these after the holiday and keep you posted on changes/improvments.

[Hubert]

#1 How harsh is miss jolt? Its my understanding the transmission is to blame for the bigger harsh bucks. But I forget automatic tranny stuff. Could be a bad ground or easy fix pressure regulator shift solenoid ????? My understanding "Fishbiting" is more subtle and quick misses like a little fish nibbling bait off a hook. Fishbiting according to Heath can be the noise suppresion electronic filter. Of course could be grounds or weak electronic connection too.

PMD can do wierd thing but if its going bad it will eventually start to stall, long crank, or no start. Won't set any SES light.

#2 Flakes are probably the tank delaminating. Just keep good filter maintenace and clean the bowl with good filter changing practices like you described. Periodically run a fuel additive to help keep other tank contamination to a minimum and all the fuel system clean.

[ccole]

#1 How harsh is miss jolt? Its my understanding the transmission is to blame for the bigger harsh bucks. But I forget automatic tranny stuff. Could be a bad ground or easy fix pressure regulator shift solenoid ????? My understanding "Fishbiting" is more subtle and quick misses like a little fish nibbling bait off a hook. Fishbiting according to Heath can be the noise suppresion electronic filter. Of course could be grounds or weak electronic connection too.

PMD can do wierd thing but if its going bad it will eventually start to stall, long crank, or no start. Won't set any SES light.

#2 Flakes are probably the tank delaminating. Just keep good filter maintenace and clean the bowl with good filter changing practices like you described. Periodically run a fuel additive to help keep other tank contamination to a minimum and all the fuel system clean.

Hubert- Well, regarding my truck, when the truck acts up (only at 50-65 mph. above or below that speed it doesnt act up), they are real harsh bucks. Actually, some of them have been hard enough to make me worry about damaging the drivetrain. Regarding your comment about grounds.... Good point, this truck came from Iowa and the undercarriage has seen lots of rust from salt. For example, when I bought the truck, I had to re-ground the front turn signal lights, due to the ground lead wire had rotted off the frame. Would it do anygood to make some heavy lead wires from the neg battery to the frame and engine block? Just curious... So, I guess at this point my plan of attack will be:
1. Check/add new ground leads
2. $58.00 fishbite fix (just in case) part #HDP1559
3. New and relocated PMD

Is that what u would suggest?

[Hubert]

Adding grounds is a good idea. Great maintenance on side post batteries is recommended for these trucks. Electronics can be hinky at times. I have 2 grounds on each battery. On mine drivers side factory goes to engine. I added one to body. Passanger side factory goes to body. I added one to engine. Clean back ground near ATF dipstick body to engine and check or add engine to frame ground.

I don't know what to tell you on the buck / fishbite? definatively. I don't know what it is on the auto tranny that does the buck. I have heard of the torque converter unlocking can cause it. I don't know what causes the PCM to command the unlock. Just thought I'd point out its my understanding "fishbite" caused by the electonic noise filter is quick lite misses in succession. Many people chase that one. Your plan is a good start but I don't think anyone is going to guarantee you'll fix it right off.

On the PMD/FSD a good remote mount is recommended for reliability. But again can't say for sure you are having a PMD issue right now.

Good luck this particular problem it seems to be a bit of target, fire, and adjust.