loss of power on highway- won't go over 45 mph!

[40Flipper]

Hello!

I'm so new to the 70 section that my truck hasn't even arrived yet! It's in customs clearance. The RI that I used drove it from the border to his yard. He said it wouldn't go over 45 on the highway.

Any ideas on why this is happening? It's a 1985 BJ70 with a reconditioned engine. The diaphragm replacement seems to be the cure-all for every problem these engines have. I've ordered a new one anyway. Any other things I should think of? Perhaps a line pressure problem like a clogged line?? I know jack about diesels but I'm reading all the threads I can!

I drove it but never got to highway speeds. Drove fine at lower speeds.

John

 

[seapotato]

Think the RI was smart enough to check if it was in low range?

 

[40Flipper]

Hmmmm.....good point. I doubt it but then again he is a mechanic. I'm gonna call him tomorrow and ask

Anything else that might cause it?

 

[bkfj40]

Think the RI was smart enough to check if it was in low range?

that was the same thing I was thinking of....that sucker would've been screaming though in low range.


bk

 

[JohnnyC]

was it just not going that fast ...or...was it bogging down slow?

like it was starving?

 

[40Flipper]

Like it was starving. I ordered a new diaphragm and also the diesel purge stuff. Heard that was a quick fix.

Also, the truck hasn't been driven much and it's mother-flippin cold up North still so I'm wonderin if the fuel has been gelled up a bit. The truck has a block heater but no heater for the fuel. Gonna put it in my garage (heated) do the purge stuff, change the diaphragm and get it out on 495 for a few exits. Hopefully that'll work.

Some fresh diesel too. Gotta blow out all the crap from the lines I think. The PO didn't drive it that much for the last year so it's been sitting in frigid temps for months

The gelling would explain the lack of flow at higher speeds/demand on the highway

 

[prado t]

Whoa, whoa whoa, Lets not get too excited . OK wait till YOU drive it and then go from there. First thing before you do any thing is dump a FULL bottle of POWER SERVICE 911, or SEA FOAM, bring a filter wrench to unscrew fuel filter to put a new one in also put the P.S. 911 or SEA FOAM in the fuel filter. IF done carefully you will not need to RE-PRIME injector pump.

Mine does maybe 28km/h 5- low at 4000rpm. SCREW the purge s***! Compression Ignition engines are a tad bit more simpler to diagnose

 

[45Kevin]

Our diesel doesn't gel unless it gets really cold, by our standards.

The first thing I'd check for is a dirty filter, both air and fuel.

ditto what prado said.

 

[40Flipper]

Ordered new fuel and oil filters yesterday as I planned on doing them first anyway. Hoping the purge stuff will do it as it's already in the mail. Should be easy I hope! Another Mudder recommended the purge stuff and he seems to know his stuff. I'm gonna be in VT tomorrow so might shoot up to the RI yard and take it for a run.

 

[roscoFJ73]

I guess we are talking 45 mph. Does it have any kind of smoke billowing out the back?
Anyone checked to see if the throttle cable is jammed?

I would spend some time looking it over and finding the exact nature of the problem.

 

[40Flipper]

No smoke

Didn't get to see it today. Will pick it up next week and fix it or will do a 400 mile drive going 45 mph!!

 

[Gold Boy]

do a search on "seafoam" in the diesel section, i added a can just to my fuel tank and noticed a big difference, some others fill there fuel filter full and noticed a big difference. napa carry's it.

 

[hoser]

If rolling 35's, then an indicated 45mph is normal.

 

[40Flipper]

Truck has 31's tho!!

 

[prado t]

Better stick with a gas cruiser LOL

 

[David*BJ70]

John. I personaly drive this truck at the speed of 100km/h.

I already tell you (and to Olivier) to change the fuel filter and put a full bootle of sea foam in the filter. (I even bring him a sea-foam bottle)

Some of our Cruiser sleep in the driveway for 4 to 6 months each winter and still peppy at spring when we crack them !

I did not check the Air filter ! Did you ?

 

[40Flipper]

FINALLY got the truck yesterday! Took it for a spin. It is fine until you hit 4th gear then it levels off and acceleration stops. It has pep and plenty of power until 4th then it's very sluggish. Is it just that it's not a turbo? The Seafoam can was used and there looks to be a fairly new fuel filter on.

The truck has 31" tires and appears to have a 2.5" lift on it. I'm sure the roof rack doesn't help with aerodynamics either. I don't think 31" tires would need a re-gearing.....

 

[JohnnyC]

just throwing this out there John....
but...did you check for a governor, or speed limiter?

we had a work van in 1990 that had one...make the van seem like we were hauling 1000 brick at 58 MPH


edit:
Diesel engines? dont they all have one...i'm not that big of a diesel guy....dont know too much about them.

 

[40Flipper]

Wouldn't know where to begin to find that. Any suggestions?

 

[roscoFJ73]

Wouldn't know where to begin to find that. Any suggestions?

Have you checked to see if the pedal cable is pulling the throttle lever back to its full position?
You should be able to get 4100 rpm in neutal.
If the cable is ok ,it may need the fuel turned up

Has the air filter been checked? Exhaust pipe flattened or bent?

Do the easy stuff before touching anything on the pump.

Potions in a bottle probably wont help a rebuilt engine as it should be reasonably clean inside