losing power and rough idle in traffic. ´75 bj40

[costaricancruiser]

Hey there. I´ve just got to ask if anyone might have a quick and dirty idea about what may be happening with this particular problem. 1975 BJ40. With a newly rebuilt B engine. oooh boy.

Recently I´ve noticed that I´m losing power occasionally while in stop and go traffic. I´ll have to keep the engine revving in order to maintain power and if I don´t I get a really rough idle with stalling occasionally. However it has always fired right back up and I can continue on my way. Also, while on the highway at cruising speeds this hasn´t happened at all...

Fuel filter looks good, and all the lines from the injection pump to the injectors have been bled. I don´t know if the injection pump can get weak or something before crapping out...same with the fuel pump. Could it be the injection pump or fuel pump going...or a bad tank of fuel I got in Guatemala...

So now the copmlications really begin I´m in Mexico about 600 miles south of the US border. I´ve only got a set of metric wrenches and a pair of vise grips and a screwdriver or 2.

So if you´ve got any ideas they sure would be appreciated.

Thanks,
Jim

 

[lostmarbles]

Hey there. I´ve just got to ask if anyone might have a quick and dirty idea about what may be happening with this particular problem. 1975 BJ40. With a newly rebuilt B engine. oooh boy.

Recently I´ve noticed that I´m losing power occasionally while in stop and go traffic. I´ll have to keep the engine revving in order to maintain power and if I don´t I get a really rough idle with stalling occasionally. However it has always fired right back up and I can continue on my way. Also, while on the highway at cruising speeds this hasn´t happened at all...

Fuel filter looks good, and all the lines from the injection pump to the injectors have been bled. I don´t know if the injection pump can get weak or something before crapping out...same with the fuel pump. Could it be the injection pump or fuel pump going...or a bad tank of fuel I got in Guatemala...

So now the copmlications really begin I´m in Mexico about 600 miles south of the US border. I´ve only got a set of metric wrenches and a pair of vise grips and a screwdriver or 2.

So if you´ve got any ideas they sure would be appreciated.

Thanks,
Jim

Hi Jim.

I suspect some sort of fuel restriction caused by "bad fuel".

The last time I experienced this it was caused by bacteria converting the diesel into filter-clogging muck. (Wasn't my vehicle.)

Perhaps change the fuel filter (even though you think it is OK) and cut open the old one to see if it was restricted by gunge.



PS. One would expect a fuel restriction to cause problems when your vehicle is attempting to use fuel at the fastest rate - like when climbing a steep gradient. But when I drove that vehicle with the fuel-bug problem it was "running rough and stalling" almost randomly.

 

[Big Blue 84BJ60]

This has happened to me a couple of time, but only when i get off the highway the trucks starts to shudder the oil preassure dropps off and the truck stalls unless i keep it revved like you stated.

I've tried everything and I've even rebuilt the entire engine (Loose precup once the head was off so I decided to rebuild) but it still happens for some reason. I think it has something to do with the fuel lines / fuel pump or the edic these are the only part of the truck left untouched, this only happens after a long hard run with hot oil and even still it doesent happen often its like theres a gremlin screwing with s*** I would like to figure out but can't

does it happen often on your b engine?
What is your oil pressure when your engine dies/shut down?
Has it happened before?

 

[Big Blue 84BJ60]

oh I've tried changing fuel filters although it has been a while and i have a 84
3b engine early build date 3 bearing camshaft if it helps at all

whats the best additive to get rid of diesel bacteria?? alcoholic type??

and ive always assumed the low oil pressure was due to the rough idle no worries there my oil pump is new.

not trying to hijack this thread only trying to help
hope you get this figured out
cheers
jon

 

[lostmarbles]

.......
whats the best additive to get rid of diesel bacteria?? alcoholic type??

Wayne has a suggestion in post #13 in this thread Jon. (I haven't got a clue myself.) :

https://forum.ih8mud.com/diesel-tech-24-volts-systems/269770-3b-varying-power-what-going-here.html

But I wouldn't try any treatment at all before confirming that bacterial-contamination is indeed your problem.



PS. The other day I cut open an old oil filter using a dremel-type tool with a very thin metal cutting blade. And you could do the same with a fuel filter to check for "gunge". (It only took me a few minutes.) My reason for cutting open the oil filter was just to check on the quality of the "relatively-unknown-brand" & "made-in-China" filters that I'm using. ----- And BTW, I don't think "made-in-China" is reason by itself to discard something as trash. In fact I'm happy with the quality of the filter I cut open and even well-known brands like "Valvoline" are made-in-China too. The filter I opened up was dirty/used (rather than clean/new) because I'm too tight to sacrifice a new one. But at least it belonged to the wife's car where the engine oil isn't quite so black as mine. (But I use the same brand on my cruiser for both oil and fuel. - I think it is "Pro" brand - which hardly inspires the level of confidence that the Chinese manufacturers - with their use of English Dictionaries - obviously expected it to. (But I'm getting into my old habits of mumbling on and on and on and on .............sorry)

 

[Big Blue 84BJ60]

lol I've been told I mumble too...

But still this is a mystery that no one can explain and it has happened to a couple people on mud here I guess we live by the rule driver till she dies or you get a good problem and this one doesnt happen all the time so ... (lol thats all I got) iguess this thread is to be continued
although it could be a worn out creassent in the timming gear cover and as the oil gets supper hot (rare occasions) we encounter this problem

other than the things iv'e stated i'm up s*** creek without a paddle LOL

 

[rendrag]

Bugs

The cheapest way to get rid of bugs is a little gasoline.

 

[simonliew]

you may begetting air in your fuel system,check your fuel lines for cracks and pin holes by blowing air into your fuellines.
Also check your primer pump,if it is old and leaks when you pump it,air can get in.
Simon