3.0L sputtering and won't go over 2k rpms

[osfd401]

Having issues with a 3.0L GL-MMDA. Motor sit for roughly 3 years. I changed normal parts and drained the gas before attempting to fire. Mechanical fuel pump was bad so swapped to electric pump. Rebuilt carb. It fired up, ran it down the water bout 20-30mins. Running bout 3500rpm and would sputter. Went to turn around it died (didn't have idle dialed in yet). From there on it will run smooth up to 1800 rpm but above that it starts backfiring, bucking, sputtering etc. New coil same issue. So far I've replaced cap, rotor, plugs, wires, fuel filter, oil change, rebuilt carb (took back apart to blow out and make sure everything was right), and fuel pump. Adjusted timing by ear and it wouldnt help or hurt the 2k rpm issue. Compression is good 150-155 across all cylinders. Ran off fuel tank and 5gal container. Thanks.

 

[alldodge]

starts backfiring, bucking, sputtering etc

Howdy

The key one here is the backfiring. When a motor is running at higher rpms and starts to backfire its from it not getting enough gas or the timing is way off. Since it was running OK for 20-30 minutes, I think your carb got some crud in it and its clogging the venturi's

 

[ThomW]

I would also check timing with a light. Might seem alright by ear and still be enough off to cause you issues when it starts advancing.

 

[osfd401]

Here is a video from today. And I took carb back apart after the 20-30 mins running right and then messing up, blew everything out and seemed to be good.

 

[osfd401]

Can't get video to load. Sorry. And I had a friend drove while I adjusted timing. It would never go above 2k rpm

 

[alldodge]

You have posted 3 times now so you should be able to link the vid.

 

[Scott Danforth]

welcome aboard

coils never go bad, so you just wasted $35 (Let me clarify, only 1 out of a million coils changed is ever bad)

set the timing correctly with a timing light. you will never be able to set timing by ear. Ever. your most likely about 10 degrees too far advanced, which will pop like crazy, and destroy your motor

start with the tank. after 3 years, fuel is no longer fuel. the crud that was in there dried and is now in your fuel system.

when you cleaned the carb, pass a fine wire or fishing line thru every passage.

 

[osfd401]

I will get a timing shunt and then set with a light. And yea coil didn't help but oh well. If it's a kinda cheap part, I'm up for trying it out at this point. While he drove today I played with distributor and never got it over 2k. Took carb back off and apart. Took the 4.5 power valve out and put in a 6.5. Everything else seems good in carb. And the gas tank I drained and I have ran it off a 5 gal jug also so that should eliminate tank issues. Thanks everything for responses.

 

[osfd401]

I am picking up a timing shunt today and will get my time set with a light. I have been thinking about this and what controls the advance and how can I check the advance?? Would that be the ignition control module, I know on cars that's what controls it but cars also have the 4 wire plug to receive signal from computer. Thanks

 

[osfd401]

My timing is not advancing. After viewing it with the light today I figured that out. Took module to autozone. They tested and said it failed. Replaced with an ACdelco 1965 (duralast brand). Still not advancing. Replaced the pickup and still the same. Did I get a bad module?? What else can be an issue?!? Thanks

 

[alldodge]

After timing is set, are you removing the shunt to check advance?

 

[osfd401]

Yes

 

[alldodge]

There is only two things that control timing, the module and the distributor. Have a look here for testing procedure

http://forums.iboats.com/forum/engi...es/278257-volvo-est-timing-procedure?t=271407

 

[osfd401]

Replaced module yesterday with Volvo OEM. Same symptoms. When setting the base time (engine running, connect shunt, then 12v, time, remove shunt) it never dropped rpm like I had read it should. Please help and save me the big mechanic bill or being forced to sell (ole lady ain't happy)

 

[alldodge]

Sorry by not providing good info, if this was a Merc I would have a much easier time. This doesn't help you just letting you know were I'm coming from.

The motor is a 3.0 GL-MMDA but this doesn't tell me if it uses 12V to place in base timing but think it should. So if its not going into base timing with applying 12V and jumping the other two wires, then either the module is bad or something else is not functioning correctly

 

[osfd401]

Thank you. And everything I read says 12v should put it in base timing mode.

 

[osfd401]

I am still having issues. Broke down and took boat to mechanin. He looked at it, checked compression, removed manifold and check it, etc. He stated "you need a carb". Before I drop $500 on a new carb i would like other opinions. I had a really reputable carb guy look through mine yesterday, bolted it on and same issues. I have a video but can not figure out how to upload.

 

[alldodge]

You can upload pics but not vids. Vids need to be linked from places like you tube.

Your previous issues were indicating a carb problem, and that leaned us for rebuild or replacement. You also stated your timing was not advancing, has this issue been resolved?

 

[osfd401]

Timing has been set the proper way and it advances. Carb has been rebuilt. And carb was gone through again yesterday by a very reputable carb guy. Do you think this carb might just be unrebuildable? May have sit too long and got too gummed up? I will try to figure out the linking of video.

 

[alldodge]

. Do you think this carb might just be unrebuildable? May have sit too long and got too gummed up?

A carb is not unreliable it can only get worn out to the extent it can no longer be rebuilt, and this doesn't happen very often. If the carb is gummed up then the carb was not properly cleaned. Carbs have very small idle circuits and you either need an ultra sonic cleaner or need small wires to pass thru the ports