1995 M977A2

[jarhead65]

ok,thought of myself as a pretty good mechanic but today i am re thinking that statement....this 8v92 is giving me a migraine. cannot figure why at 1/2 throttle it cuts out puff black smoke and starts slowing.checked fuel pressure and its good,changed out all three fuel filters,looked for turbo leaks and to no avail...could someone please let an old crayon eater know what i am missing? i would be glad to be schooled by anyone.

 

[NDT]

Do you have DDEC4 engine control?

 

[jarhead65]

Do you have DDEC4 engine control?

DDEC3

 

[NDT]

Well you know how this goes, plug in the DDDL and “pull the codes”.

 

[jarhead65]

Well you know how this goes, plug in the DDDL and “pull the codes”.

no codes exept for low oil pressure,but since been resolved. one other issue was with temp sensor and also resolved. yes sir step by step,please continue. i am more than willing to take any advice you can give.

 

[NDT]

Ok good. My next efforts would be to make 100% sure there are no hairline cracks in any fuel hoses that could admit air. As fuel demand is increasing the air entrainment get so bad the engine falls on it’s azz.

 

[jarhead65]

Ok good. My next efforts would be to make 100% sure there are no hairline cracks in any fuel hoses that could admit air. As fuel demand is increasing the air entrainment get so bad the engine falls on it’s azz.

could be a smart place to look seeing it sat for 8 yrs....lol i will give it a look see. anything else you can think of would be great,i will be back on later after i look at all the lines.

 

[NDT]

Sometimes the fuel pickup tube inside the tank gets rust pinholes on trucks that sit like yours has.

 

[jarhead65]

Sometimes the fuel pickup tube inside the tank gets rust pinholes on trucks that sit like yours has.

it has a new tank on it,yeah the old one was quite rusted...not even sure what the heck that was in it...couldnt tell the smell lol

 

[Mullaney]

it has a new tank on it,yeah the old one was quite rusted...not even sure what the heck that was in it...couldnt tell the smell lol

.
Had to make a comment of some sort.
Hoping to learn along with you.

 

[fuzzytoaster]

It's a fuel delivery issue but for sanity sake take a look at the exhaust for wet stacking since you've already serviced the filters. If the exhaust is carboned up it could impede air flow causing it to burn rich then choke out. There may be enough flow to idle it but at higher rpm it can create back pressure. Knowing how most MV's spend their lives idling.. also it's easy to check with a borescope or popping off the exhaust.

I believe NDT is on the right track as I too had a 8V92TA back in the day that did the same thing and it was junk in the tank accumulating at the pick up tube starving it at higher rpm. Does this truck of yours do it immediately or after running for a period of time?

 

[jarhead65]

It's a fuel delivery issue but for sanity sake take a look at the exhaust for wet stacking since you've already serviced the filters. If the exhaust is carboned up it could impede air flow causing it to burn rich then choke out. There may be enough flow to idle it but at higher rpm it can create back pressure. Knowing how most MV's spend their lives idling.. also it's easy to check with a borescope or popping off the exhaust.

I believe NDT is on the right track as I too had a 8V92TA back in the day that did the same thing and it was junk in the tank accumulating at the pick up tube starving it at higher rpm. Does this truck of yours do it immediately or after running for a period of time?

it does it at all times exept at idle no load.i believe it's a load issue,hot or cold....but i will check for incumberances. thank you sir.

 

[US6x4]

This happens in the gas engine world when the inner layer of fuel hose delaminates from the outer layer and is allowed to collapse when the suction gets stronger. You can't see it and there are no leaks to detect. I suppose it could happen to any rubber fuel line under sunction...

 

[Mullaney]

This happens in the gas engine world when the inner layer of fuel hose delaminates from the outer layer and is allowed to collapse when the suction gets stronger. You can't see it and there are no leaks to detect. I suppose it could happen to any rubber fuel line under sunction...

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Especially so when the vehicle runs perfectly at idle - and hacks and coughs as speed increases. Replacing fuel/gas hoses is about the cheapest possible fix for the problem. AND if that rubber line is 20 years old, it may have outlived its useful life.

 

[silverstate55]

Especially so when the vehicle runs perfectly at idle - and hacks and coughs as speed increases. Replacing fuel/gas hoses is about the cheapest possible fix for the problem. AND if that rubber line is 20 years old, it may have outlived its useful life.

Also the hardest thing for a vehicle owner to accept, if the hoses look serviceable on the outside.

 

[jarhead65]

.
Especially so when the vehicle runs perfectly at idle - and hacks and coughs as speed increases. Replacing fuel/gas hoses is about the cheapest possible fix for the problem. AND if that rubber line is 20 years old, it may have outlived its useful life.

yes sir i agree,i will be doing so asap just for sh*** and giggles,and for sanity sake.and i resemble the remark about outliving useful life......lol

 

[jarhead65]

i want to say thank you for you all responding to my problem. I will update you as progress is made.