volvo occasionally backfires

[gino45]

Ok, we're talking about a 151 Volvo here. Took it out first time in awhile and it only wanted to run about 2,000 rpms. Push the throttle up and it would immediately bog down and die unless I pulled back on the throttle. Eventually got to about 2200 rpms with only occasional backfires. Through the carb, I think.

Read the recent posts and I looked at oil--looks clean to me, certainly not milky. Checked the fuel filter--no water. Then I pulled the plugs. They were all dry and clean. Then I spun the motor and no water in the cylinders, so not everything is bad!

Anyway, revs right up when not under load, but in gear it's a no go.

What do I do next, folks?

 

[tunahuntr1]

Re: volvo occasionally backfires

Ok, we're talking about a 151 Volvo here. Took it out first time in awhile and it only wanted to run about 2,000 rpms. Push the throttle up and it would immediately bog down and die unless I pulled back on the throttle. Eventually got to about 2200 rpms with only occasional backfires. Through the carb, I think.

Read the recent posts and I looked at oil--looks clean to me, certainly not milky. Checked the fuel filter--no water. Then I pulled the plugs. They were all dry and clean. Then I spun the motor and no water in the cylinders, so not everything is bad!

Anyway, revs right up when not under load, but in gear it's a no go.

What do I do next, folks?

I would seriously check my ignition wires,especially if they are old,a real loss of power and if they arc can cause backfire.Hope I helped...8)

 

[calwldlif]

Re: volvo occasionally backfires

Check you accelerator pump

 

[Don S]

Re: volvo occasionally backfires

How it revs in neutral is a non test. A V8 engine only running on one side will run over 8000 rpm.
Here is a list of the things that can cause the problem. In the past year alone each of these problems has been the cause of someones low rpm problem.

 

[gino45]

Re: volvo occasionally backfires

Wow, that's quite a list! Many of these can be eliminated as this machine has lots of power. It revs right up, I don't believe it's a lack of compression. Me thinks it's fuel supply related. Thanks! I'll check it out. Only thing is its frustrating to have to relaunch each time to see if it's working now, since it runs fine while in neutral.

 

[JS Machine 1]

Re: volvo occasionally backfires

I am having the same problem man-and I mean exactly. mine won't go over 1200 rpm under the same circumstances you listed above. I rebuilt both carbs. I'm not sure if they are side or down draft solexes, but one of those kinds. I didn't see anything in there that would keep the motor from running. Everyone(including the guy I bought it from) is pointing towards the ignition. I have a bosch distributor with points. [previous owner said points), I didn't see anything wrong with them except for normal wear---but that doesn't mean anything. I replaced the points($9) and I had to order a new cap and rotor button. I put in new plugs also. I have a new condenser but I'm not gonna go that far unless the boat still doesn't run. The only thing I haven't checked from the list above is fuel pressure and clogged exhaust outlets. come to think of it I'm gonna pick up a little cheap fuel psi guage from the parts house today before I try the boat. one thing I knew but had forgotten is that you can't leave the ignition on with a points system. If the points happen to be closed it will ruin them.

I'm gonna put it in today and maybe it will run right.

It all the sudden did this, It ran fine on the fourth--but, I carried alot of people and the boat was under a heavy load. mine is a 73 model volvo aq 130 with a 270 outdrive. If you have more questions or want to share experiences my email is craashnburn@aol.com.

 

[JS Machine 1]

Re: volvo occasionally backfires

well, the stuff I mentioned above worked. we took it out today and it didn't miss a beat!