fuel pressure regulator /pump question

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26scarab

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Discussion starter · #1 · Aug 26, 2005

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A couple of weeks ago I had an electric pump fail. When I installed the new one I figured the regulator already has been set so I never checked fuel pressure. At the same time I installed a "supersucker" spacer. I ran the boat once, just cruising nothing over 4000 rpm's with no problems.

Ran it in a poker run a couple of days ago and with a full tank of gas it was a couple of hundred RPM's down, and at one point actually dropped from 5600 to 5000 for know reason. Someone told me later it sounded like the motor was missing. Checked the plugs and they are all black.
The question I have is it possible for the fuel pressure to be too high with the new pump or is the carb spacer just pulling too much fuel ? I didn't get too much time to play around though the sea pump pulley came apart and ended my day.

 

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Mudball

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#2 · Aug 26, 2005

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I am also running a Supersucker, but it didn't change my plug reads that much...

I am running on the rich side, but not super rich.

CFM is the man on these. He did mention that some need to back off on jetting 1 or 2 sizes. That's not much.
===
Sorry about the sea pump pulley...Is it possible that the pump caused the rpm loss from drag, before the pulley let go? That's hard to imagine a pulley just coming apart on it's own!
Kent

 

C

cfm

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#3 · Aug 29, 2005

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26scarab said:

The question I have is it possible for the fuel pressure to be too high with the new pump or is the carb spacer just pulling too much fuel ?

Click to expand...

Both.

However, the fuel psi needs to be looked at first. Check it since, yes, the psi could be different.

The SS increases signal to carb and thus 'pulls' more fuel out of it. Usully only a jet # or two different, BUT, that is usually.

Always have to check things when something is added. :bigsmile:

 

C

cfm

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#4 · Aug 29, 2005

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BTW: check the fuel pis when the boat is running. IE: the pump is getting max voltage.

Yes, the set psi can be different when alternator not charging vs when charging.

Voltage at the pump has everything to do with the pumps output pressure and volume capabilities.

 

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26scarab

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Discussion starter · #5 · Aug 29, 2005

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Spent all day Sat. checking things. I found a ton of things wrong. Most of this summer the boat has only been run 3800-4000rpms cause I've had my spare stock 300+ hour drive on it. So I really haven't kept up on the upkeep.

Well ,
First thing is I pull all the plugs, they were very fat and one was carbon fouled and the one other one wasn't even firing , you could see it was gas washed. That explains the 5mph loss and the motor just falling on it's face.
Second thing I check fuel pressure, it's got 8.5 lbs and the float levels are way too high. That explains the richness.
Third thing is I decide to check the timing , well let's just say I'm glad all the other things wen't wrong or I'd be looking at a broken motor right now. The dist. must have loosend and the timing was at 40deg. NOT good .

Well I've reset the fuel pressure at 7 , adjusted the float levels, put in a new set of plugs and set the timing at 34 , so now I just have to go out and test it.