My poor tahoe q4 has wot problems

R.ERICDAVIS

Cadet
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Jun 9, 2013
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3 weeks ago i bought a 2004 tahoe q4 with a 4.3 190 hp v6 .. In the water under a load my wot is only 3000 rpms . From what i understand it should be from 4400 - 4800 .. Out of the water or in neutral position it revs to 4000+... It has a electric fuel pump an carb.. Not mpi ! Any help is appreciated !!!
 

achris

More fish than mountain goat
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Re: My poor tahoe q4 has wot problems

Post up the size of the prop (pitch, in inches) and the size and rough weight of the boat. And the drive ratio. Should be written on the port side of the drive-shaft housing. Will be either 1.81:1 or 1.62:1

Has the boat ever reached 4400-4800? Revving in neutral is not really a good indication.

Chris......
 

thumpar

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Re: My poor tahoe q4 has wot problems

Out of the water RPM doesn't matter. Check to make sure you have the correct ratio drive first.
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

It had a (stock ) 23 pitch on it an a buddy that has a simular boat other than 5.7 has a 19 pitch so i borrowed a 19 an ran it but it dot not change a thing... It has a 1.81 out drive ratio
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

Chris no it has not ever got over 3000 or 3100 rpm an according to spec i think its about 2800 lbs loaded. First time out i had about the max weight of 1100 in it an last time it was just me an the wife and it done no diff.
 

achris

More fish than mountain goat
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Re: My poor tahoe q4 has wot problems

Back to basics... Check compressions, spark plugs, timing..... You know the drill?

Chris.......
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

I changed the plugs .. They all looked normal , no discoloring like they were not firing .. It starts rite up an idles smooth ... I was told the 19 pitch should give me way more low end power . I expected it to give me more rpm due to less load ... Boy was i wrong ... What else ya got ???
 

thumpar

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Re: My poor tahoe q4 has wot problems

Timing and weights in distributor. Have you checked compression?
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

No compression check just yet... A guy that does some of my work on my vehicles said it could be a timing issue ... I will have him try that next week i hope ... Then go deeper in to stuff like compression .. Thanks for the response !!!
 

achris

More fish than mountain goat
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Re: My poor tahoe q4 has wot problems

Timing and weights in distributor. Have you checked compression?

The V6s haven't used weights in the dissy for timing advance since 1983.. It could be a timing advance problem, but you will need an advance timing light to check it...
 

achris

More fish than mountain goat
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Re: My poor tahoe q4 has wot problems

No compression check just yet... A guy that does some of my work on my vehicles said it could be a timing issue ... I will have him try that next week i hope ... Then go deeper in to stuff like compression .. Thanks for the response !!!

Compressions should be the first check, not a 'deeper into it' issue....
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

O well if i can get it in the shop i will have it all done at same time ... I was going for the saving money factor to keep the wife off my butt !!! Lol
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

Ok here is a update . It has average 165 lbs. Compression on all 6 holes !!! Changed plugs fuel filter and high dollar fuel pump just incase ... With all that by playing with the trim i made it to about 3500 rpms before it was trimmed up so much it started dropping speed ... Any ideas ???
 

Don S

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Re: My poor tahoe q4 has wot problems

Ok here is a update . It has average 165 lbs. Compression on all 6 holes !!! Changed plugs fuel filter and high dollar fuel pump just incase ... With all that by playing with the trim i made it to about 3500 rpms before it was trimmed up so much it started dropping speed ... Any ideas ???

Well, now you know changing high dollar items is a bad method of troubleshooting. Try this HOW TO: Testing your boats fuel system.?/ 283269

Or, hook up an outboard tank with new clean gas in it, directly to the fuel pump and go for a run and see if you get the rpm back.
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

One of the guys working on it suggested some racing fuel to see if it helps.
 

thumpar

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Re: My poor tahoe q4 has wot problems

You need to start diagnosing. Race fuel will not help anything. The only reason for high octane fuel is in high compression/high turbo motors. If you aren't pinging it will not effect a thing.
 

R.ERICDAVIS

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Re: My poor tahoe q4 has wot problems

I will see about trying that this weekend !!! Thanks for the info...
 

RyanSS

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Re: My poor tahoe q4 has wot problems

Have you tried running the original prop to see if anything changes?
 

kjunmed

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Re: My poor tahoe q4 has wot problems

Just had the same problem with our 09.... has the boat sat up for any amount of time? I had to rebuild the carb, then the fuel pump fuel filter was starving the carb for fuel. It was clogged. I took the original fuel pump fuel filter out and installed an inline fuel filter. Also you may want to check the fuel line from the tank to the fuel pump, if it is bent it may also be starving the fuel pump....

Also if this doesn t work, make sure you are getting fire to all cylinders by pulling a plug wire at a time, and if the engine starts missing they are firing.

last thing it could be is the gray wire on the Tach, disconnect it, there are instances of that wire shorting out and causing the engine to not run WOT....

I hope this helps...
 
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