Bogging down...how to fix? mechanic needed for advise

[86mazdapickup]

First let me start off by saying that Im not sure if bogging down is the correct term, my dad refered to what my truck was doing as "bogging down" so I figured he could be right.

What happens is this, upon startup and maybe a half a mile of driving it its fine,then it starts to loose power and gets jerky on me and my rpms will start to drop. It will do this until im down to a crawl. So I turn it off and coast for a little bit and start it up again and the problem is temporarily fixed. Then after another half a mile of driving, it starts doing it again and the problem continues.

Another thing that I should point out is that it gets worse in the rain. But if im just sitting there at a light or parked somewhere with the truck running it runs fine. I don't think its the fuel pump, however I could be wrong. It doesn't make and wierd humming noices that i heard could be caused by a bad fuel pump. yet again i could be wrong.

So what could it be? Theres probably a number of things that could be causing this so where should i begin? Im mechanically inclined so I plan on doing it myself unless its something I can't possibly do without the right equipment. help me please. thanks, greg

[johnnynumfiv]

Could be the fuel filter, I had the same thing with one of my MG's, it would run then crap out, and clean the carb if there is one. The getting worse in the rain is a wierd thing though. Seems like a wierd problem all together.

[86mazdapickup]

thanks for your response..so whats the deal with the fuel filter? where is it and is it accesible? can it be cleaned or does it need to be replaced? thanks.

another thing i forgot to mention is that when i first got it which was a week ago it only bogged down on when i got on the highway. it was dry at the time too. so i'm thinking it might be a combination of things, but i could be wrong. But ever since it rained the other day it continued to do it. maybe there's water somewheres that hasn't dried up yet? who knows..im sure someone does. thanks

[johnnynumfiv]

Also could be water in the gas. For the fuel filter, I don't know where it is on the truck, but you can just replace it, they are around $5usd.

[86mazdapickup]

i don't think its water in the gas for this reason. as i get low on gas and fill up everday the problem doesn't get better after i fill up. now wouldn't the problem get better as i continue to fill up and make the gasoline to water ratio
more on the gasonline side after every fill up? does that make sense to you?

[johnnynumfiv]

That makes sense. I would check the whole fuel system, try to get some of the injector cleaner or engine cleaner that you pour into your gas, and see if that helps.

[baddabang]

THis happened alot in our plow truck. We went over everything and after changing the plug wires and the distrubitor the problem was gone. I doubt its the same in your truck, but its worth looking at i guess.

[Matra et Alpine]

Sounds like breakdown in insulation in the ignition side of things - could be the low tension or high tension side.
Check all the wires and clean them up. Any cracks or splits replace them.
Check the plugs, check the white insulator at the tip isn't cracked or broken.
If the engine doesn't mis-fire before "bogging" then pay close attention to the lead from the coil to the distributor.
Also check all the earth straps for the engine.

What engine and ignition system is in the car ?
There are a few voltages and resistance you can check if it's not a complex ECU. If it's all in the ECU brains, take it to a garage and get them to plug it in to the diagnostic computer. 30 seconds will find the problem.

OTHER things it could be as stated, fuel filter, most likely if it hadn't been for the wet making it worse.
Is the tank a closed system ? If it's open, make sure the breathers aren't' blocked. An easy test for that is to run it with the cap OFF. If it runs fine then the tank is becoming a vacuum and preventing fuel flow.

How quickly is it bogging down ? Could be crankcase pressure. To be that bad it would be obvious that it was pressurising by feeling the oil filler opening with your hand.


The other (worse) is it coull be rings/bores as the oil thins it is less able to maintain the seal. But again. not somethign you'd expect worse in the rain

[pimento]

I'd be trying the electricals, given rain makes it worse. My mini has the bottom of a plastic milk bottle over the distributer to keep it dry in the rain. Always try the easy/cheap things first. It's never a bad idea to buy new leads and filters given the age of your car.