Surging issue on my 93 dually.

[Thompsoned67]

Hell everyone. I am a relatively new diesel owner. I have a 93 Chevy 1 ton dually. Recently it has started a new issue, which is the lunging or surging that I have heard others talk about. It only happens when I am driving, it idles fine and does not stall out. Sometimes it happens for a few minutes, and other times it will last longer, and sometimes it will not do it at all. Since my truck is a 93 I have no pmd. I have replaced fuel filter, checked for steady fuel flow and thoroughly checked all connections. Injectors were replaced about three months ago and glow plugs a month ago, as well as the glow plugs relay. Not being an experienced diesel owner is showing. Any advice would be greatly appreciated. Thanks in advance.

[DmaxMaverick]

Welcome aboard!

To begin, check the tranny fluid level, and for air in the fuel return outlet at the injection pump (temporarily install a loop of clear tubing and watch it while it's running). Once the engine is started and running, glow plugs are not an issue.

[Thompsoned67]

First of all, thank you for the response. As for the transmission fluid, I know that it is full. I just checked all fluids yesterday. As for the air in fuel, I will try your suggestion and see what happens. I was told that the system should bleed itself when running. Is this correct, and if not what is the best way to get it bled completely?

[DmaxMaverick]

The system will bleed itself of remaining air, once it's bled initially and the engine is running. The problem is air may be continuously introduced into the system due to leakage. This can happen from a leak prior to the fuel lift pump when the lift pump is working properly (like running out of fuel), or from anywhere if the lift pump fails to provide a positive flow. A plugged fuel filter can also cause fuel starvation, and air intrusion, despite fuel lift pump function.

If the symptoms seem to occur more often with less fuel in the tank, the fuel lift pump may be weak, or there's a problem with the fuel tank sending unit or plumbing. A lower fuel level in the tank requires more (however slight) suction to draw it to the lift pump. This will exploit or exaggerate any weakness (leak) in the upstream system.

[Thompsoned67]

Well I have replaced fuel filter, checked for air in fuel system and all is good. As it turns out the surging issue happens when the truck is in Overdrive. I have figures out that if I manually shift the truck into Drive the surging goes away. Transmission otherwise shifts good and fluid levels are good. I have a trans cooler on the truck as well. I was told by a local mechanic , that knows very little about deisels, that the only electronics on my truck has to do with the transmission. But others have told me that there is nothing electronic on my truck. At this point I am stumped...but need it to work rite.

[Thompsoned67]

I forgot to mention that my check engine light is on at idle...but when I am accelerating it will go out.....never seen that before. Not sure if the two are related, but I'm thinking that it's possible. No codes show up at all.

[Robyn]

Pull the codes and see what it's not happy about.

Another check...
Open the water drain line(Fuel filter) up near the front of the engine by the water crossover.

(Put a short hose to the valve and stuff if in a suitable container to keep from making a mess.

Start engine...then open the valve.

Fuel should flow from the hose and ENGINE SHOULD "NOT" STALL

If engine stalls or starts running rough or surging ...this indicates a lift pump issue...

[JohnC]

As it turns out the surging issue happens when the truck is in Overdrive. I have figures out that if I manually shift the truck into Drive the surging goes away.

Your '93 dually does not have a check engine light. The only warnings come from the trans controller. Your symptoms could be caused by torque converter clutch issues.

[DmaxMaverick]

Your '93 dually does not have a check engine light. The only warnings come from the trans controller. Your symptoms could be caused by torque converter clutch issues.

I don't know about federal emissions trucks, but every ~1993 CA emissions truck has an SES lamp. I can't imagine the federal smog trucks not having one, even if it's inactive, or partially inactive, but in every case, it is reactive to DTC retrieval. L56/S code powertrains have EGR, which is monitored/controlled by the ECM, and the TCC is monitored by the ECM as well. L65/F powertrains have the TCC monitored by the ECM. Parts search shows ECM and PROM available for them, with no distinction for smog region or powertrain code.

An intermittent SES lamp could indicate TCC slippage or TCC solenoid response (could also indicate harness or ground issues). Pull the DTC's to know just what it's complaining about. Only surging in OD/4th may indicate slippage, or it could also be a clutch/band. I don't know if the TCM monitors, or is capable of monitoring, (shaft) speed differentials, such as in later models. They are subject to higher torque input when in OD under load, such as maintaining speed or accelerating at highway speeds. Thinking back to the 88-93 GM Diesel and gas trucks (agriculture and gov.), any time surging occurred in OD, a tranny rebuild was short on the horizon, and the cause was usually a band. Continued driving just increases the bill for the rebuild, as further contamination and heat affects more internal parts.

[JohnC]

I had a '93 HD. It had no monitors or controls on the engine. In fact, it was a standard, so it had no monitors on anything. I seem to recall all the vehicles < 8600# were 6.2s that year. Don't know nothing about Kalifornia stuff.

[DmaxMaverick]

I had a '93 HD. It had no monitors or controls on the engine. In fact, it was a standard, so it had no monitors on anything. I seem to recall all the vehicles < 8600# were 6.2s that year. Don't know nothing about Kalifornia stuff.

I don't think any 6.5L's, at the time, were specific to CA. Perhaps a CA smog PROM, but that's not an issue if there's nothing to plug it into. 1993 (among other surrounding M/Y) powertrain options were a mixed bag. The 6.5TD was available in C1500, but not K1500 or Blazer/Yukon/Suburban (I was shopping a 6.5TD Blazer at the time, and was turned off by the new EFI options upcoming). Essentially, only 2 WD models and 8600+ GVWR pickups. The 6.2L remained available until January 1993 builds, when the 6.5TD was available, but not in all models. Typical GM transition period, beginning in 1987.5 and continuing to 1993.5. Since about 1980 (maybe earlier, IDK), every tooling update has seen this chaos of a transition. At any rate, the only common denominator in regards to computer control or monitoring I can identify is smog equipment and/or 4 speed auto, with MFI 6.5L's. You're right, in that there's nothing to control or monitor on your non-smog, MFI, manual tranny truck so, no computer, and no need for a (active) SES lamp.