2.9l bogs at highway speeds

[sweetsride]

well, lets see if i can explane this or not, on my b2 with a 2.9l, i can 4x4 it all day but when i go onto the highway to go to or from the trail, i get it up to speed 75klm or so and it starts to bog down, it feels like it loading up on fuel, it spits and sputters untill i let of the gas, let it slow down a bit and then it gose a bit and dose it again... sometimes it backfires a little then gose good for a few klms.

i have new plugs, wires, cap, rotor, fuel filter, air filter,and checked the timing.


any help would be good as i plan on going on a trip the first week of aug that is 100klms just to the trail head

Thanks
Kris

 

[Big Jim M]

Do you notice any kind of exhaust sound that might be unusual? Could be a partially stopped up cat or muffler..
Big JIm

 

[sweetsride]

the cats are no longer there, and as for the muffler, its a glass pack/cherry bomb, and i dont think its plugged, but worth a look


thanks
Kris

 

[Big Jim M]

Ok then thqat is out.. Next is the backfiring and spitting/sputtering.. Backfiring is a result of the juice being turned off and then back on again.. Could be a coil.. could be really worn plugs.. possibly coil wire... cracked cap... pickup in the dist..
Just need to recheck all of the lectrics..
If it didn't backfire I'd be looking into nother new fuel filer..
Big JIm

 

[sweetsride]

well.. let me clear up the backfire, it only back fires when i let off the gas, and its not really a backfire, more like extra gas burning out of the exhaust, kinda a poping sound


Kris

 

[Psychopete]

Have you pulled codes yet? There no indicator light like on later models to notify you when the computer sees a problem. You might have something in stored memory to help pin point the problem, or even might see something faulty during KOEO. Look in the technical library for ECC-IV diagnostics.

Pete

 

[AllanD]

To me it sounds more like a fuel delivery problem

I've had more than my share of clogged fuel filters
and chocking spitting sputtering and even back fireing are part of the whole "poor delivery" problem.

And though I know he has recently replaced his filter that doesn't
eliminate the possibility of a bad batch of fuel clogging another one

And if it isn't then it's likely that the fuel PUMP is the issue.

It's time to put a fuel pressure guage on it, preferably one
with a LONG hose and if necissary duct tape it to a wiper arm
so you can SEE it while driving

Fuel pressure is supposed to go UP with throttle application
(inversely proportional to intake manifold absolute pressure)

If you reach a point where fuel pressure falls off you have a pump problem

AD

 

[TwoWhels]

It is an 87 right?
You should have 2 fuel filters on it.

It has the 2 fuel pump system?

Sounds like mine till I found the second filter and changed it.

 

[AllanD]

It is an 87 right?
You should have 2 fuel filters on it.

It has the 2 fuel pump system?

Sounds like mine till I found the second filter and changed it.

IF your '87 had a filter inside the resevoir cannister someone swapped it in to your later truck OR someone at the factory screwed up.

But your explanation is possible.

AD

 

[sweetsride]

well, i jus came back from my trip, and it did the same problem but worse, would not hold in 5 on the highway and in 4 you had to have you foot to the floor or it would bog and sputter.

it dose have the duel fuel fitlers on it, which i havn't noticed till now, the in line one is new, new plugs , wires, cap and rotor, the in tank fuel pump is 3 years old, did it when the new fuel tank went in.


any ideas, i am going to get a fuel pressure gage and try that out


thanks
Kris

 

[CraigK]

disconnecttheO2sensordisconnecttheO2sensordisconnecttheO2sensordisconnecttheO2sensor

CraigK

 

[ckblum]

I was having a similar problem but I thought it was just because my engine was getting over heated and cranky. I would drive it around town and stuff and do some trails but the first time I drove to work on the highway I was highly doubting I was gonna make it on time/if at all haha. Similar symptoms though, when I first got on I was going about 100 but then after about 5-10 min it dropped to about 70-80 and sounded real bad like a sputtering lawn mower and I had my foot to the floor just to keep it at 80. I went down to 4th and my RPM's wouldn't climb at all. My rad has a pinhole in it but I put some rad stop leak in there and I think it helped a bit. I thought it was an overheating problem because when I pulled off the highway and popped the hood there was a bit of smoke and it was real hot and after we sat for 10-15 minutes the truck had its power back for a short time. Also the lifters sounded like they were gonna blow through the hood, but thats a whole other problem I guess, they were just louder than they are around town.

 

[Rammunition360]

it sounds like you have better response with it to the floor...so im guessing with everything said it would have to be shitty fuel delivery...

 

[ckblum]

Negative!!

 

[derek54401]

"backfire noise"

that noise that you hear on the overrun is not a backfire. that is normal with a glasspack. yes it is a sort of popping noise, but much more airy than a backfire. that noise should also occur during engine braking down a hill, but it will not be as pronounced.