I've owned my 6.5L for two days, and it's already stalled 3 times!!

[arveetek]

I just brought home my first electronic 6.5L Tuesday night. This will primarily be my wife's vehicle. It's in great shape, but has 165K miles. It runs like a top most of the time, but tonight it shut off 3 times while driving, all in less than a mile. It's kind of hard to start sometimes, either hot or cold, and it doesn't appear to be glow plug related, and I'm sure it's not the ignition switch.

I'm sure it's the FSD, I've read the posts above, and I've been following the 6.5L's problems for years. So I was expecting this.

Here's my planned list (in no particular order):

1. Replace the FSD with either the Sol-D, Kennedy's remote mount kit, or Heath's remote mount kit (see my other post about these choices).

2. Replace the OPS and do the relay mod.

3. Replace the fuel pump.

4. Replace fuel filter.

The IP was replaced by the dealer around 30K miles ago, but I'm not sure when/if the fuel pump or OPS was changed, or how long ago the fuel filter was changed. The OPS and fuel pump are probably fine, but I just want to do it all right the first time. I don't want this thing stalling on my wife!

Along with the stalling, it's hesitated a few times, and it has a weird hard-start issue. Most of the time it fires right up when cold, but not always. Sometimes it doesn't want to start when warm, either. A little tap on the accelerator makes it start right up in either case. I'll bet this is FSD related, too, eh?

Any thoughts or suggestions? Am I missing anything?

AFAIK, no codes have been set, and no CEL.

Casey

[arveetek]

After doing some more searching, I just just discovered Kennedy's fuel pump/OPS harness. Doing the simple $5 relay mod would be a great improvement over the factory setup, but I like the idea of having the automatic fuel priming taking place everytime the key is turned on. Has anyone else used this harness? (http://www.kennedydiesel.com/detail.cfm?ID=402)

Casey

[twaddle]

Hi Casey,
First of all call into your local Dealer and ask them for a print out of the full warranty repair history. A dealership that is of a helpful nature will usually be pretty helpful, those that aren't helpful will probably give you hassle later so you may end up shopping around.

The stalling problems can be aggravated by an accumulation of several small faults ranging from poor batteries, bad connections to the PMD and or fuel pump failing.
Check as many connections from the batteries, cables and multiplug connections as you can lay your hands on. Also check for loose connections especially ground points.
It may help to check voltages at various points, a voltage drop may indicate a poor connection or even a bad wire/cable causing resistance.

I increased the number of ground cables because I didn't like the original factory set up of the ground cables at each side of the engine. This seemed to improve things for a while.

Is the lift pump operating OK? You should hear it buzzing when the ignition switch is turned on, it should continue to run when the engine is running. You may need to lie under the truck to hear it or you can feel the pump buzzing with your hand.

Good luck and keep us posted.

Jim Twaddle
Biggar, Scotland

[arveetek]

Thanks Jim!

I printed out a copy of GM's service history when I purchased the vehicle. The only two items that showed up were an IP replacement 30K miles ago, and a windshield wiper repair 3K miles ago. I'll bet the whole IP didn't need replacing, probably just the FSD was bad.

I'm wanting to eliminate ALL possible causes of stalling, so I'm going to go ahead and replace the fuel pump, FSD, and OPS. I'll be sure to check all wiring and grounds while I'm at it.

If this were just my truck, I'd do one thing at a time and see what happened, before condemning the FSD. But since this is my wife's main vehicle, I want to be sure it's safe and reliable. The FSD is a known design flaw, so I will take care of that once and for all.

Casey

[john8662]

Hey Casey, Congrats on buying what I've always wanted!

I like the method of replacing the already suspect parts on these rigs.

So, get a new OPS, I think Autozone has a lifetime warranty version, thats what I have. While you're buying the the OPS make sure and get the correct socket for the job. There is a Oil Pressure Sender socket that is the correct size and depth to get the OPS out, otherwise you'll break it off. The socket is stepped and fits multiple senders, including ours.

For your FSD, I don't really have much advice there, I'm in the same boat, I'm torn between what to use. I'm even playing with fire, in that I left the FSD on the injection pump, and will still leave it on the pump (it's still under warranty) until it dies. When it finally does die, then I'll swap in my FSD Cooler equipped with a new FSD on it into action that I keep in the glove box.

I like the idea of the KD OPS harness, saves the trouble of splicing your existing wiring, and coming up with a relay.

One good thing I can think of on the 95, it's got the older electronics, letting us check codes on the fly. You can even bleed the fuel on a 95 by opening the fuse center under the hood and removing a relay and shunting a couple contacts (I've got a drawing that I can send).

I think that you're onto the right track though, replace the FSD and you'll see reliable service again and better starting.

[DmaxMaverick]

On a '95, you can run the lift pump with engine off w/o jumpering.

Set E-brake (chocks, if on a hill or questionable E-brake), turn key to "run" (don't start), move shift lever to any position other than P or N, and turn key to start. The pump will run, and the starter won't engage. Very handy for bleeding the filter and checking the operation of the pump with the OPS out of the loop. If the pump runs this way, and not while the engine is running, the OPS circuit is suspect. If the pump runs with engine running, but not with this method, the prime/start relay circuit is suspect.

[rjschoolcraft]

Originally posted by arveetek:
After doing some more searching, I just just discovered Kennedy's fuel pump/OPS harness. Doing the simple $5 relay mod would be a great improvement over the factory setup, but I like the idea of having the automatic fuel priming taking place everytime the key is turned on. Has anyone else used this harness? (http://www.kennedydiesel.com/detail.cfm?ID=402)

Casey I have one on my Suburban. It's a great idea and works well. I'd highly recommend this over a splice job because it is "plug 'n play".

Casey, it was nice to speak with you on the phone a few minutes ago. Good luck with your decision.

[arveetek]

Okay, I've ordered an FSD cooler kit, OPS harness, and new lift pump from Kennedy diesel. This should make for a very reliable vehicle.

Thanks for all your advice!

John,

Yeah, this is an awesome vehicle! I absolutely love it! I didn't know so much luxury could be combined with a diesel truck. It's the best of both worlds. Plus, with the short wheel base, 2 doors, and 1/2 ton suspension, it'll be the perfect 'family' car for just my wife and I. We're really enjoying it (other than the hard starts and stalling!). It rides like a dream. I think it's much better than my parent's Lincoln Town Car! I'm also amazed at how quiet it is inside. You can barely even tell it's diesel-powered, even at idle. Normally, I prefer to hear the diesel rattle, but for the family car, this is just right.

Ron,

Thanks for your time in answering my questions. It's always great to talk to fellow diesel enthusiasts.

Casey

[20050627|3|008327|000043|65.183.99.20]

Originally posted by DmaxMaverick:
On a '95, you can run the lift pump with engine off w/o jumpering.

Set E-brake (chocks, if on a hill or questionable E-brake), turn key to "run" (don't start), move shift lever to any position other than P or N, and turn key to start. The pump will run, and the starter won't engage. Very handy for bleeding the filter and checking the operation of the pump with the OPS out of the loop. If the pump runs this way, and not while the engine is running, the OPS circuit is suspect. If the pump runs with engine running, but not with this method, the prime/start relay circuit is suspect. Does this work on a 94 as well?

[DmaxMaverick]

Tacklewasher

Unfortunately, the '94 was [is] the "red-headed step child" of the 6.5's. It was a transition year for the EFI's, and there aren't many out there. They are very different than the '95 and later years, and aren't much compatible with any other year. I have heard of a couple times where the '94 I/P, EFI, and PCM was upgraded to a later year's components, making the pumps more readily available, and in many cases, less expensive. I don't have any experience with the fuel delivery end of them, but there are a few here that do.

Give it a try. If it works, great. If not, jumper the relay or meter/hotwire the pump and check for flow and pressure.

[tom.mcinerney]

Casey-
I think JK's OPS harness is a good plan ; it's more advanced than a simple relay , which may pay off in better LP duration. I spent quite a while setting up mine with a relay.

Check that the filter cannister has the small cylindrical nylon filter screen in place over the smaller of the central tubes , resting on the top lip of the larger one. Suggest get a new one from , say Gomer's. If the filter has a metallic cap on the bottom , that's the old style fuel heater...might get a newer plastic-based version of the heater from Peninsular or Avant, as the old ones leak. A new oring for the heater wouldn't hurt.

Regardless of whether you follow above advice, I STRONGLY suggest you renew the ignition switch . All the OPS+FSD power and a lot of other stuff
runs thru the ig sw , and the contacts do appear to burn and contribute to untimely demise of FSD+OPS.

And i agree with above suggestion to add another engine ground , and be sure to clean up the OEM rear psgr wire harness ground(s) by trans dipstick, as that is a key component. If the rear pkg/brake lights are fluky , add another frame ground .... You do have Dr Lee style batt terms, right?

[arveetek]

Originally posted by tom mac 95:
You do have Dr Lee style batt terms, right? Thanks for the advice, Tom. I have Dr. Lee's battery terminal upgrades on my '81, but not on the '95 yet. I will. I'm also considering upgrading the batteries. They look new and function fine, but they're only 850 ca (650 cca). I prefer 1000 ca batteries myself.

I'll check the other items you mentioned as well.

The truck has stalled on me several times this weekend. It really only stalls after being driven for a while, shutting it off for a couple of hours, and then heading down the road again. It'll run all day without a hitch after a cold start, but if you shut if off, let it sit awhile, and then start it back up, it'll stall three times in under a mile, and then be fine for a while. It has a bit of a stumble/miss at times as well.

My old '81 sure doesn't have this problem! Just a little glow, a flick of the ignition switch, and she starts, every time, and never stalls! With the amount of money I've already spent, I could have swapped in a mechanical pump! But I want to try and keep it stock and get it functioning properly before I use that option. I'm confident I can work these problems out.

Casey

[arveetek]

I serviced the '95 yesterday....changed the oil, changed tranny fluid/filter, and checked a few things out. Turns out the lift pump wasn't working. I opened the bleeder valve with the engine running and it immediately stalled...had a hard time starting after that. The pump did run when turning the key to start with the tranny in drive, but wasn't running when the engine was running.

I temporarily rigged up the fuel pump to run with the key on, and it runs much better now. It was stumbling and sputtering at times when accelerating hard. Solved that problem. However, it stalled on me 4 times last night! On two different occasions, it stalled twice after driving a short distance after it had sat for an hour or so. So the fuel pump, or more specifically, the OPS, isn't causing the stalling.

Apparently I've got several issues to work out. I received the package from Kennedy last night, so I will be able to install the new FSD, cooler, and fix the fuel pump correctly with the OPS harness soon.

I'm surprised the truck ran at all without a functioning fuel pump.

Casey

[JohnC]

Originally posted by arveetek:
I'm surprised the truck ran at all without a functioning fuel pump. There's a transfer pump internal to the injection pump that can pull enough fuel through a new filter to make it run pretty well. What's missing, however, is the cooling effect from the extra fuel flowing through the housing. Now you know why the FSD failed... ;)

[arveetek]

Originally posted by JohnC:
Now you know why the FSD failed... ;) I was thinking about that. The IP didn't have much fuel pushing through it to keep the FSD cool. I was surprised the FSD was acting up with only 30,000 miles on it. Now I know. The IP still looks like brand new. Who knows how long the lift pump has been out.

Casey

[arveetek]

I installed the new FSD and cooler yesterday afternoon. It was a real piece of cake to install, took all of 30 minutes. I mounted the cooler in front of the driver's side battery where there is a large hole in the radiator support that will allow outside air to flow over the cooler.

I'm happy to report that the truck didn't stall last night! My wife and I have been attending a meeting at church each night this week, and for three nights in a row, it stalled two or three times right after leaving church. Last night, it didn't stall, hesitate, shudder, stumble, stutter, or anything of that nature. I'm confident it's completely fixed for good now.

I believe that the original FSD, which had 30,000 miles on it, started to fail prematurely due to an inoperating lift pump. This prevented the fuel from cooling the FSD. The reason, I believe, that the truck would stall after sitting for an hour or two is because the engine heat would soak into the FSD, causing it to short out until it cooled off a bit from driving again.

Another symptom I've noticed is that with the old FSD, I couldn't hold the engine at a desired RPM when sitting still. I'd try to hold the engine at 1500 RPM (working on the a/c system), and it would race up to 3000, so then I'd let off the throttle and it would go back to idle. It was very hard to control. Now I can hold the RPM's wherever I want.

This weekend I'll install the new OPS harness I got from Kennedy.

Even with the stalling problems I had, I sure loved driving the Tahoe! What a nice, comfortable vehicle. Now with the stalling problems fixed, I love it even more!

Thanks to all of you here on the Diesel Page. Because of you, I knew immediately how to fix the problem, even though it was my first electronic 6.5L. If it weren't for you, I'd probably be pulling my hair out by now! Instead, I didn't worry one bit, and was confident I could fix the problem in no time.

Casey

[Barry Nave]

I couldn't hold the engine at a desired RPM when sitting still. I'd try to hold the engine at 1500 RPM (working on the a/c system), and it would race up to 3000, so then I'd let off the throttle and it would go back to idle. It was very hard to control. Now I can hold the RPM's wherever I want.

Hmmmm, I still can't hold a unloaded RPM's :confused:

[arveetek]

I installed Kennedy's OPS harness today. Installing the actual switch itself was rather difficult, simply due to the location of the factory OPS, and I had to add a tee fitting to retain the stock switch to drive the guage on the dash, and install the second OPS from Kennedy to run the fuel pump. After that, the wiring was a piece of cake.

Now when I turn the key on, the fuel pump runs for a few moments, and then shuts off until the engine oil pressure closes the switch and keeps it running. There's also a manual switch to run the fuel pump when changing fuel filters.

I also installed a new lift pump and changed fuel filters, so the manual switch came in handy to bleed the fuel system. Engine started right up with no hiccups or anything of the sort.

The truck has not stalled once since installing the remote-mounted FSD. I believe I have now made this vehicle very reliable and feel much better about letting my wife drive it anywhere.

Thanks again to John Kennedy and to all of you on this board!

Casey

[j7l2]

ARVEETEK,
Where did you connect the Kennedy harness to get a hot when switch is on power supply? I can't find a place in engine compartment that isn't hot all the time.
Thank you,
jimo

[arveetek]

Originally posted by j7l2:
ARVEETEK,
Where did you connect the Kennedy harness to get a hot when switch is on power supply? I can't find a place in engine compartment that isn't hot all the time.
Thank you,
jimo Actually, I did connect the large ring terminal (B+) to a constant hot source: one of the two accessory lugs on the rear of the fuse/relay center on the driver's side inner fender. The smaller wire, the one for the ignition source, I ran inside the cab and connected to an ignition blade on the lower interior fuse/relay panel. I cut and spliced that wire...didn't feel like using the enclosed fuse tap.

Casey