Help needed. Loss of engine power

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Help needed. Loss of engine power

October 11, 2020, 02:06:13 am

We just had our headgasket replaced on our 8.3 with all work completed tonight. Supposed to be leaving for the coast tomorrow for a week trip with the family. Leaving the shop had an intermitten squeeling noise that went away after a couple blocks but from the start had a very large loss of power. Thought it was in my head so headed out of town for a test drive. Takes an incredible amount of time to get us to speed and feels like I am running at 1/4 power.

I checked the fuel solenoid valve and found it going all the way up. All boost & inner cooler lines look good. I cannot find a clamp loose or a cracked boot. The engine fuel filter was changed today and the primary changed last year about 1,500 miles ago. Air filter is new. Waste gate hose seems to be a little loose so I tightened the clamp and will have to wait till morning to see if that made a difference(neighbors). My pac brake is off and the ram is all the way in(?).

Any help or tips to save our families vacation would be greatly appreciated.

[Edited topic title to add "engine" for clarity - Michelle]

Re: Help needed. Loss of power

Reply #1 – October 11, 2020, 08:03:39 am

I would have the air cooler test you may have a crack in it they are known to cracking from twisting I have the same problem we had just talked about it in a question I asked And wrote on. Look it up it was on a couple of days ago. Engine power do you find your coach lazy look it up or maybe a hose with a rip in it they didn't leave a rag in the 4" pipe going from engine to air cooler that they plug so no dirt would get into the system While they worked on it things of Have accidentally Got Left behind by accident

Re: Help needed. Loss of power

Reply #2 – October 11, 2020, 08:58:38 am

I echo Cape Bretoner's thoughts...

No specific ideas here, but when a "new" engine problem pops up immediately after having mechanical work done on the engine, the most logical suspect is something done incorrectly during the recent mechanical work.

What shop or mechanic replaced the head gasket? Are you able to go back to them and say "Something is not right"?

Re: Help needed. Loss of power

Reply #3 – October 11, 2020, 09:45:32 am

I saw your post and kept thinking "I remember something about this..."

On our old Foretravel, the water pump was seizing. It made a squealing noise at start up, which would go away after a few minutes (probably the belt slipping.) I remember being shocked at the power loss from the failing water pump. Just before I replaced it, we started to leave for a trip, I could tell the coach lacked power, and we immediately went back to the shed.

Matt B

Re: Help needed. Loss of power

Reply #4 – October 11, 2020, 12:57:14 pm

Thank you for the help everyone. I was still hoping to find something simple that they missed but it is not looking that way. My immediate thought was a rag also! It is a good local shop and I will be taking it back in tomorrow if I can't find something today.

Thanks again!

Re: Help needed. Loss of power

Reply #5 – October 11, 2020, 01:32:51 pm

Keep us updated on what thy find.
Bill

Re: Help needed. Loss of power

Reply #6 – October 11, 2020, 02:09:50 pm

Quote from: WILDEBILL308 – October 11, 2020, 01:32:51 pm

Keep us updated on what thy find.
Bill

Will do! Just test drove it to make sure tightening the hose from the wastegate didn't help. No go.

My lower back is giving me to many problems right now to start taking off the turbo hoses looking for blockages.

Hopefully solved tomorrow.

David

Re: Help needed. Loss of power

Reply #7 – October 11, 2020, 02:25:39 pm

I would start with a new set of fuel filters. The age is just as important as miles. Stuff can grow and cake over time. It is an annual maintenance at minimum. You would need to do it soon anyway so it isn't really a wasted effort.

Re: Help needed. Loss of power

Reply #8 – October 11, 2020, 04:07:09 pm

The lift pump on your Cummins has a fairly high failure rate so check pressure out of the pump. Low pressure can damage a mechanical pump over time and fairly rapidly damage a CUPS injection pump. Pump is cheap and easy to replace.

Pierce

Re: Help needed. Loss of power

Reply #9 – October 11, 2020, 04:12:51 pm

Sorry you are having a problem. Fuel shut off solenoid is a prime reason, but you have that covered.

Another is if you have King Throttle control, it will go to Limp-mode if King cannot see a ground on the positive wire going to the brake light bulb. Bulb burned out, wire disconnected will prevent King from seeing a ground path on the hot wire, through bulb filament to ground. Open bed and see if King does not fully pull throttle cable. You can also attach a pull wire to rotating throttle part at injector pump and manually pullup to see if more throttle I available without King.

This situation is a good reason to have a dash boost gauge and a fuel pressure gauge which only become valuable when we have a problem.

Let us know what you find.

Re: Help needed. Loss of engine power

Reply #10 – October 11, 2020, 06:51:06 pm

Quote from: Eric & Alena + 3 – October 11, 2020, 02:25:39 pm

I would start with a new set of fuel filters. The age is just as important as miles. Stuff can grow and cake over time. It is an annual maintenance at minimum. You would need to do it soon anyway so it isn't really a wasted effort.
Very good point that it is time anyways and a simple thing. Just having a hard time with the fact that it was running great on Tuesday before they started. Thanks

Re: Help needed. Loss of engine power

Reply #11 – October 11, 2020, 06:52:54 pm

Quote from: Pierce & Gaylie Stewart – October 11, 2020, 04:07:09 pm

The lift pump on your Cummins has a fairly high failure rate so check pressure out of the pump. Low pressure can damage a mechanical pump over time and fairly rapidly damage a CUPS injection pump. Pump is cheap and easy to replace.

Pierce

Pierce, i just changed the lift pump last year with a lot of help from Chuck due to the old one leaking. I do have a spare if they want to go down that road. Thanks!

Re: Help needed. Loss of engine power

Reply #12 – October 11, 2020, 06:55:01 pm

Do NOT just start throwing parts at it.

Find a mechanic familiar with the old/your mechanical Cummins 8.3 to diagnose the issue.

Re: Help needed. Loss of engine power

Reply #13 – October 11, 2020, 06:58:13 pm

Quote from: Barry & Cindy – October 11, 2020, 04:12:51 pm

Sorry you are having a problem. Fuel shut off solenoid is a prime reason, but you have that covered.

Another is if you have King Throttle control, it will go to Limp-mode if King cannot see a ground on the positive wire going to the brake light bulb. Bulb burned out, wire disconnected will prevent King from seeing a ground path on the hot wire, through bulb filament to ground. Open bed and see if King does not fully pull throttle cable. You can also attach a pull wire to rotating throttle part at injector pump and manually pullup to see if more throttle I available without King.

This situation is a good reason to have a dash boost gauge and a fuel pressure gauge which only become valuable when we have a problem.

Let us know what you find.

Barry,
I 100% agree with you on adding gauges. I thought I was out of the woods last year with my leaking pump but going down this road again I will absolutely be adding these gauges!

With my sons help I reached down and pulled the throttle cable quickly to full stop then had him do it from the pedal and it seemed to travel fully from what I can see. Do you know if this safety feature would only play in while driving??

David

Re: Help needed. Loss of engine power

Reply #14 – October 11, 2020, 07:02:08 pm

Quote from: wolfe10 – October 11, 2020, 06:55:01 pm

Do NOT just start throwing parts at it.

Find a mechanic familiar with the old/your mechanical Cummins 8.3 to diagnose the issue.

Brett,

Appreciate it! I don't plan to. The shop that does the work has been really good and knowledgeable. I have good faith they will troubleshoot it in the morning and get me going. I was hoping to find it myself knowing that it most possibly had to do with the connections they made. Thanks.

David

Re: Help needed. Loss of engine power

Reply #15 – October 11, 2020, 07:04:22 pm

Quote from: Familyrig – October 11, 2020, 06:51:06 pm

Quote from: Eric & Alena + 3 – October 11, 2020, 02:25:39 pm
I would start with a new set of fuel filters. The age is just as important as miles. Stuff can grow and cake over time. It is an annual maintenance at minimum. You would need to do it soon anyway so it isn't really a wasted effort.
Very good point that it is time anyways and a simple thing. Just having a hard time with the fact that it was running great on Tuesday before they started. Thanks

Eric and Alena,

Quoted that wrong somehow, sorry. Using my phone and eyesight is not that great anymore...

David

Re: Help needed. Loss of engine power

Reply #16 – October 11, 2020, 07:32:54 pm

David,

I am not suggesting that the shop you are using is not qualified. My point is that a qualified tech on your mechanical 8.3 Cummins beats your or our "arm chair" suggestions on how to spend your money.

While most of the suggestion here ARE things that need to be eliminated, a good tech should just SMILE and say-- yup know that!

Re: Help needed. Loss of engine power

Reply #17 – October 11, 2020, 08:27:22 pm

I find that when you go into any situation, whether it be a diesel shop or an adult store, if you have some of the lingo down and are halfway confident, you won't get taken advantage of as much. That is, unless you want to be.

Pierce

Re: Help needed. Loss of engine power

Reply #18 – October 11, 2020, 09:41:51 pm

David, I am not 100% clear on your findings.

Sounds like you have King Throttle control. Is this correct?

Did you try to drive with bed up and observe that full throttle almost fully rotates the valve on the injector pump?

If not fully rotated, does manually rotating valve by pulling on a string/cable bring back full power?

If you are doing things while in neutral, I am not sure it would simulate real driving to resolve low power problem

For why King Control goes into limp-mode if it cannot see brake circuit ground:

King wants to be sure it will know when brake pedal is being pressed.

So it can disable cruise control and turn off throttle

King tests brake light circuit by looking for ground which it sees through the light bulb filament where one side is grounded.

If it sees ground it assumes brake light circuit is working.

When it does not see ground, it must assume brake lamp circuit is powered by 12volt positive or wire is broken.

This is my understanding.

BTW, we and others have driven (even at highway speeds) for days with a disabled King Throttle by manually pulling on valve.

We can also simulate lower power by disconnecting King to brake light wire.

We had exactly the same low throttle (panic) situation, where we replaced fuel filters and did other things, but the problem ended up being our fuel shutoff solenoid partly opened from binding. To drive, we pulled it fully open and kept it open with a cable tie. Drove normally and when it was time to turn off engine, we cut cable tie. Did this for a week until we could get to Cummins for a replacement solenoid which turned out to be a revised larger solenoid that came with a different solenoid mounting bracket. If broken solenoid did not open at all, engine would not run. It was the partial open that hid the solenoid problem.

Barry

Re: Help needed. Loss of engine power

Reply #19 – October 12, 2020, 12:23:12 am

Quote from: Barry & Cindy – October 11, 2020, 09:41:51 pm

David, I am not 100% clear on your findings.

Sounds like you have King Throttle control. Is this correct?

Did you try to drive with bed up and observe that full throttle almost fully rotates the valve on the injector pump?

If not fully rotated, does manually rotating valve by pulling on a string/cable bring back full power?

If you are doing things while in neutral, I am not sure it would simulate real driving to resolve low power problem

For why King Control goes into limp-mode if it cannot see brake circuit ground:

King wants to be sure it will know when brake pedal is being pressed.

So it can disable cruise control and turn off throttle

King tests brake light circuit by looking for ground which it sees through the light bulb filament where one side is grounded.

If it sees ground it assumes brake light circuit is working.

When it does not see ground, it must assume brake lamp circuit is powered by 12volt positive or wire is broken.

This is my understanding.

BTW, we and others have driven (even at highway speeds) for days with a disabled King Throttle by manually pulling on valve.

We can also simulate lower power by disconnecting King to brake light wire.

We had exactly the same low throttle (panic) situation, where we replaced fuel filters and did other things, but the problem ended up being our fuel shutoff solenoid partly opened from binding. To drive, we pulled it fully open and kept it open with a cable tie. Drove normally and when it was time to turn off engine, we cut cable tie. Did this for a week until we could get to Cummins for a replacement solenoid which turned out to be a revised larger solenoid that came with a different solenoid mounting bracket. If broken solenoid did not open at all, engine would not run. It was the partial open that hid the solenoid problem.

Barry

Barry,

I am understanding what you are saying in regards to the brake light circuit, still not sure why it would put me to partial throttle by not sensing ground? Also you state you can drive at speed by manually pulling on a valve? I am not sure but are you bypassing the throttle (assuming not) or is there another valve i should look into rigging up if this is the problem?

Again thanks for all the help.

Re: Help needed. Loss of engine power

Reply #20 – October 12, 2020, 12:34:39 am

Here to throw another thought on the table.
I had similar problem with our old 1989 in that it took "forever" to get up to speed. Then the coach would slow WAY down (I could walk backwards faster).
Took it to a shop that was familiar with my engine setup. He took the coach down the road for a test, turned around and came back.
Crawled under the back end with a wrench and a pail. Turns out both fuel filters were performing just fine, but the check valve just before the first filter was "kinda" plugged with crud about 4" back into the supply line.
Seems that if a coach is allowed to set too long without having a full tank of fuel or being treated periodically, that then algae and tank crud can slough off the tank walls.

Re: Help needed. Loss of engine power

Reply #21 – October 12, 2020, 01:57:14 pm

Fixed!!!! Thanks to all for the help. They didn't tighten the lower intercooler hose. Two mechanics working on it and one didn't realize the other had loosened it. I saw the pipe left in place during the work so I didn't think to check the lower connections....

Easy fix that I should have found. Again thanks for the help and we are on our way to Dillons Beach!!!

David

Re: Help needed. Loss of engine power

Reply #22 – October 12, 2020, 02:30:50 pm

Everyone had their fingers crossed. Glad it was a no cost fix and you are on your way. Safe traveling.

Pierce

Re: Help needed. Loss of engine power

Reply #23 – October 12, 2020, 11:01:18 pm

I always have to remind myself of the KISS theory. In my head I was already replacing the turbo...lol! Everybody have a great week.

Re: Help needed. Loss of engine power

Reply #24 – October 13, 2020, 01:20:19 am

A cloud of dust and a Hardy high O Silver, mash the motor and have a great time😎👍

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