Engine/Transmission (1994 - 1998) Rough running engine

[KEdenfield]

I have a 94 2WD auto that has more than 365K miles and no mods. I've had it about 2 years for a daily driver and had no problems, but yesterday after work it took a couple more turns of the starter to fire it off then it imeadiatly started runing rough. RPM or gear dosn't make a difference and there is almost no power. I just got through running a 500 mile road trip two days earlier and got 23. 5 mpg and also did not have any issues that morning on the way to work.



Changing the fuel filter did not make any difference and I still have to replace the fuel lines and strainer. It seems odd that there is a sudden degidation of performance from morning to afternoon and seems to be permanant.



I loosend the injector lines at the pump one at atime and 1/6 cause the engine to almost stall while 2/3/4 caused the engine to smooth out.



If that's not it, I suspect maybe the timing slipped when shuting down the engine yesterday morning. Would a bad injector cause missing/rough running?

 

[hsmith]

I would say that with 365k miles and if the injectors are originals, they certainly need to be tested. Can't see how they would fail overnight though. Slipped timing will cause rough running and white smoke also.

 

[The patriot]

check the return line

 

[KEdenfield]

One problem is the fuel solenoid blew its guts out. I think this is why there was no power. After ziptieing the fuel cutoff lever up, I ran it and had power back, but stil rough through the rpm range. Pinching off the fuel return to tank line did nothing but I went ahead and replaced the overflow valve, which made no difference.



Do you mean the injector return line? I don't see how the damaged 'fuel return to tank' line would cause any problem other than a wet spot on the ground?



How do I pull the injectors to inspect them and do a cyclinder compression test?



Still need to check the fuel strainer.

 

[hsmith]

A leaky return will allow air to enter after engine shut down and cause hard starting. Don't think it can cause rough idle.
You can pull the injectors, but they will have to go to an injection shop for testing.

 

[The patriot]

Mine started/idled fine, but would fall on it's face if you stepped on it.

 

[GAmes]

I think you have a batch of bad fuel. I had over 500k on the original injectors before I replaced them. I never had a rough running engine and you could run them today if you wanted. So much fuel had been pushed through them that the holes were enlarged and I got smoke like 370s. I had a fuel solenoid that didn't pull all the way up. The only symptom was it ran out of power when pulling a trailer up a hill. Otherwise it ran and idled fine. If you have gone over 300k miles the timing hasn't slipped, it would have slipped long ago. I've had mine reset 3 times and it has never slipped from stock, or the advances.



Did the rod pull out of the plunger or did the solenoid itself split?

 

[KEdenfield]

The rod pulled out of the plunger. There is a small clip still on the rod and it snaps back in the plunger, but will pull out very easily. If someone had a burned up coil I could use their plunger on my coil and it would still work.



Strainer was dirty but not clogged. Need to replace the streainer to lift pump elbow as its just a regular lengthof hose that is crimped over. Been like that since I've had it so I guess it flowed for a while. Fuel hose is on the way also so I'm trying to eliminate fuel leaks as the culprit for the stumble the engine has.

I'll be pulling the bed to replace the tank lines and pull the sender to check for cracked pickup tube also.



The abrupt change from a perfect purring engine to the stumble I have now tells me somthing is hard broke and not a degridation of materials. I hope its not a burned valve or stuck piston rings. Are compression tests typically performed on the cummins?

 

[charlessmith]

Burned valves or stuck piston rings don't happen overnight. Likewise, I'd doubt that lines to the tank would have become restrictive overnight.

You didn't mention this, have you checked the lift pump, and have you checked
the filter screen in the fuel heater (right below the lift pump)? Check lift pump output for volume.

It sounds to me like you aren't getting enough fuel. If you had a bunch of dirt go through the system, could it have partially obstructed several injector's injection holes?

If you were close to Columbus Ohio, I'd say to bring the injectors over and I'd test them on a Bosch injector test stand.

The previous bad fuel comment may be on target.

 

[KEdenfield]

Bad fuel is highly unlikely. I filled up at my local wallyWorld and went on a 500 mile round trip two days before it started running rough and topped off my tank at the same wallyWorld when I got back that night. Also, chaning the fuel filter did not help. Strainer was not completely clogged and heater element dosn't appear melted or leaking at the electrical connector. I took it apart and it's fine. Removed the return line, but havn't pressure tested it in a bucket of water yet. Didn't appear to have an obvious leak.



I'll have all the fuel rubber replaced this weekend and then will start pulling injectors. I made a pressure gage setup for the lift pump but havn't used it yet. Lift pump puts out enough pressure to squeal the overflow valve constantly when manually priming.



One odd thing:

I noticed a hole on the fuel shutoff lever just above its pivot with a bright ring of clean metal around its circumfrence like a bolt was in it until recently. Is somthing suposed to be attached to this hole? Turns out it is missing a bolt, but the top one is tight enough to prevent the triangulare idle plate from moving.

 

[GAmes]

If you are going to replace the fuel hoses you can easily rule out bad fuel. Place the hose that would pull fuel from the tank into a container of new fuel and see if the stumble goes away. I believe the fuel you put in when you returned from the trip is bad. I once filled my boat tank with gas at a Texaco near the lake and went fishing, never had a problem. On the way home I filled the tank of my Chevy gasser at the same station and it didn't go a half mile. While I was fishing a tanker came by and filled the storage tank with gas that was about 60% detergent.



I can't make a mental image of the hole you are describing. Any way you could take a picture?

 

[GAmes]

OK, with the aid of daylight, a mirror and a flashlight I think I know what you are speaking of. There is a bolt with an 8 mm head that goes thru the "clamp" holding the lever to the shaft. I have no idea of the threadsize, but it is about an inch long. I couldn't tell if the shaft is splined, so there is a possiblity the lever has slipped.

 

[KEdenfield]

All rubber up to injection pump was replaced. Pressurized fuel tank to bleed lines and did not see any leaks. Pulled sending unit from tank. A little dirt but no plugs preventing fuel delivery to lift pump. Drained tank in to clear barrel. Looked extremely clean with only about a tablespoon of water in the bottom. I ran a paper towel around along the bottom and didn't get much dirt either so I think I can rule out bad fuel.

New fuel strainer and filter. Return to tank line removed and pressure tested. New overflow valve installed. New fuel solenoid installed. Fuel pressure at 18-20psig at idle (needle vibrating range). Valves set to 10/20. Harm balancer in good shape with all four bolts present. Motor mounts present and accounted for. Throttle linkage functional within full range, but missing return springs.



Still stumbles at all rpms. No white or blue smoke at 2800 rpm WOT in PARK. No excessive pressure pulse or flow or blowby from case breather hose at WOT.



Found that cracking #5 fuel injector did not decrease engine rpm like all others. I tested this previously, but cracked the injection lines on the pump. Turns out I couldn't crack the #5 line because the DV holder started turning before the line broke loose.

Compression test performed: #1- 435psig, #2-441psig, #3-436psig, #4-420psig, #5-426psig, #6-443psig



It apears I have a bad #5 injector or the loose DV holder (#5) is leaking. I swapped the #4 and 5 injectors to see if dead cylinder follows the injector and retorqued the #5 DV after inpecting it. I didn't have a replacement copper washer though. Where can I order these? Cummins said they couldn't order Bosch P/Ns.

 

[KEdenfield]

Almost there, I think

I can't get any fuel out of the injection pump when cracking lines on top of the delivery valve barrels. I guess all the cranking for the compression test got air in the injection pump. I had the fuel shutdown solenoid unplugged when doing that though. Manually bleed the filter housing and supply at injection pump and the return bolt from the fuel manifold. Already ran the batteries down trying to restart the truck so the're charging overnight.



I need suggestions for getting the IP primed.

 

[LVJUNIOR]

I pump the lift pump plunger until I hear the overflow valve squeek.



Even when I had the entire fuel system off and drained on the high and low pressure sides after I put it back together I followed this method and it fired on the 3rd crank

 

[KEdenfield]

I was able to get the IP primed after a 12 hour charge on the batteries. After getting it started it ran about 2 or 3 seconds before emitting a high pitched skreech for another 3 or 4 seconds then the engnie died again and would not restart. I couldn't get anymore fuel out of the injector lines while turning it over with the starter either.



The squeal sounded like it was coming from the injection pump, but I thought it may be the lift pump cratering. The fuel pressure was spiking to 50 psi but would go right back to 0 and the "old" overflow valve seemed to relieve at 12 psig. Absolutly no pressure would remain on the supply line when the manual plunger was not being pushed.



A new lift pump kept 10 psig on the supply line after re-bleeding and the over flow valve was still reliving at 14 psig so I put the new one back in and the relief pressure increased to 19psi when pushing the plunger.



By this time the batteries were too weak and the engine would only turnover slowly, so back on the charger and I see if the injection pump will reprime tomorrow. I hope what I heard was not the IP pump kicking the bucket. If so I'm going to install a 215 pump with 500K on it before sheling out for a rebuilt unit from Piers.



At least I got 1. 5 years of daily driving out of it for $3100 before spending anything in repairs.

 

[KEdenfield]

Well I guess I'll finish this out for anyone elses benefit. If the old regurgitated "cracked fuel line, melted heater element, plugged fuel strainer, fuel solenoid, etc" FIXES everybody throws out to fix your problem, try this:

Check to see if a delivery valve holder is loose. Don't loosen it, just check it by cracking the injector lines and seeing if it will turn with a pair of pliers if it hasn't already turned when trying to loosen the line.



If one or more of them turn the you may have a problem with that barrel. Don't just retorque it because you will never get the injection pump to deliver fuel. For some reason retourqing the DV holder causes the rack to lockup.



I have verified this by loosening the holder I torqued to 85ftlb afte originally finding it loose. After about 1000 starting revolutions I finally got some fuel out of the IP and the engine ran and then quit several times while bleeding the IP lines at the pumpand injectors until, again, it would not start. After removing the fuel plate I found the rack would not move unless I loosend the #5 DV holder then it would move freely untill I tighted the #5 DV holder just a few ftlbs.



Another guy had this same problem here:



https://www.turbodieselregister.com...998/168332-another-boring-fuel-problem-2.html



Although, I don't think he realized the rack was not moving and probably got taken by the pump shop. I also suspect they painted it to cover up that there was not a new (i. e. unpainted) housing assy installed. It doesn't make sense that it was running good then the next stime it started it was bad.



Although, I belive my barrel sleeve is cracked after reading this:



https://www.turbodieselregister.com...on-1994-1998/1358-failed-pump-ever-heard.html



My truck was made in 1993 so I have a very early 160hp pump.

 

[Taz]

KEdenfield, Did you ever get your issues solved. I am facing a diagnostic nightmare with my truck trying to find why it is idling rought. My started out mild and has progressed to being worse.