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dry carb

893 Views 12 Replies 5 Participants Last post by  Mild Thunder, 
F
I'm having a problem with our Baja Force235. It will start okay and then sometimes die while I'm just idleing before take off, or during take off before I plane off.

Once it dies it will not restart, unless I prime the carb. It fires right up once the carb is primed, and will run just fine. I can take off plane off, cruise etc. Maybe the problem won't happen again for 5 or more starts, but the same thing will happen again.

I thought it was the carb accel pump. So I had the carb rebuilt. But I still have the problem.

Any ideas what might be causing this? I'm thinking anti siphon ball, but have no confidence that is really the issue. Considering getting a fitting without the ball and replacing the anit siphon with that but would like your thoughts on this. By chance has anyone else had a similar issue?
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B
If you have a Force 235 it was built prior to 1990 or thereabouts. You have a Q-Jet carb. There are some plugs on the base of the carb that are prone to leaking. This causes the fuel bowl to empty itself. Had this problem with my Q-Jet. Simple fix is a 502 crate, B&M 250 and 1050 Dominator.

That is choice one. Choice two is two do a google search on plugging the Q-Jet base or wait for someone to chime in. I believe it involves using epoxy to seal. Quick search references said problem.
http://www.cadillacforums.com/forums/500-472-425-368/138270-holley-q-jet-replacement-carb.html
http://www.buickperformance.com/qjet.html
and this
http://ramchargercentral.com/index.php?action=howtoshow;id=6

Poke around a bit and you will find the fix for the leak.
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M
Sounds like the fuel pump is going.

A bad accelerator pump will usually just cause a flat spot on acceleration.
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W
ditto on fuel pump...
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F
Thanks Baddog. My Force235 is a 1989 model. Awesome boat. This is the first major problem I've had with it, and I've had it 9 seasons now.
I've already had the carb rebuilt.

I talked with one mechanic who swears he's never seen a fuel pump fail in a boat. Sounded crazy to me, everything breaks eventually.

Is there a test I can do to ensure it's the fuel pump? I'd hate to replace it only to find out I still have the problem.
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S
>I talked with one mechanic who swears he's never seen a fuel pump fail in a boat.

I have a shelf full of them.

:dead: :dead: :dead: :dead:
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F
Thanks for the clarification Jeff. :)
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B
I believe there is a cranking test for the fuel pump. Basically you unhook the fuel line to the carb and crank it while catching the fuel and measure the volume in x amount of time. You can also rig a temporary fuel pressure gauge and observe pressure to the carb inlet throughout your operation range.

Does it die if you come off plane then go back on or only after sitting?

If you let it idle for a few minutes does it starve for fuel when coming on plane then? If not that would be a symptom of the carb leaking down.

It is not legal to remove the anti siphon valve but many due this when going big power. You can punch the ball out very easily for a test then replace it if it not your problem, they are inexpensive.

Without knowing the problem better it sure sounds like the carb is leaking down.

I agree, nice boat. I have over 3000 hours on my hull. Three engines, two drives, three sets of carpet, re-done interior several times. Still looks and performs as new.
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F


Does it die if you come off plane then go back on or only after sitting?

If you let it idle for a few minutes does it starve for fuel when coming on plane then? If not that would be a symptom of the carb leaking down.
Click to expand...

I've come off plane and powered back up with no issues. I seem to notice the failure more after sitting for a while and then starting up. But it's intermittent and that's what drives me crazy.

I agree, nice boat. I have over 3000 hours on my hull. Three engines, two drives, three sets of carpet, re-done interior several times. Still looks and performs as new. [/B]
Click to expand...
3000 hours WOW!!!!!
I have 1360 on ours. Original interior and engine. Stored inside unless on the water. Get complements on it regularly. There is another F235 that boats in the same area as us and it's done up in pink barbie colors. I'm glad mines not pink. :D
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B
OK, if it ONLY does it after sitting for awhile then you are losing fuel from the carb leaking down. Review the links on plugging the Q-Jet. Mine did this as well and I have an old Blazer that does the same. If you idle for a bit the carb will fill up and it will always come on plane with no issues.

It still may be an issue with low output of the pump at idle and low RPM. By the fact you can come on and off plane with no issues rules this out but you may not have hit the right circumstance coming on/off. Do the fuel pump test at cranking speed to be sure.

At 1360 you are getting close to a rebuild! I rebuilt/replaced my engine several times and added more HP each time. In view of gas prices I may rethink this and consider not how fast I go but how long I can go. Been kicking around the thoughts of an alum block/head 383. A buddy of mine bought his Force with a 350 mag and it did OK. A light SB might give me some decent economy and still allow some decent speed. Instead of 80MPH runs I could perhaps hit 60 and afford to hold it there a bit longer. Cruise speed may be lower but overall burn rate would be much less.
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F
Are you saying that even with a rebuilt carb I could still be experiencing the fuel leakdown? Wouldn't the rebuild take care of that? :confused:

I considered a souped up 454 or maybe a 502, but that is all in the thinking stage. I would love to be able to maintain power with a small block, but not sure that's possible.

You've hit 80mph in yours!!!??? :eek: Wow!!!!! I'm impressed!!!!

Thanks for your help with this.
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F
Finally got this solved. You guys were right on. Fuel Pump. The gauge showed 2 to 3 pounds pressure, with three being the minimum needed for operation. Installed a new pump and pessure jumped to 7 to 8 pounds. Perfect.
I did some cruising last weekend and no issues. :D
We're cruising again ....just in time for the 4th. Yippeee. :D

Thanks for all your help guys!!!!!!!
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M
Your welcome, glad to hear you got it going.
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