Low speed stalling

[Boston Habba]

1987 175 v6 carbs<br /><br />Engine has been running great until the other day. Filled up at fuel dock and within 10 minutes started to have a problem. Had to pass through a big no wake zone so was at near idle for about 10 minutes. Engine died but restarted fine, ran good at higher speed, and didn't give me a problem until I was going very slow to pickup my mooring. Stalled again.<br /><br />Took a closer look today. Switched to a portable tank with fresh gas from another source - same problem. Starts OK. Idles fine out of gear. Idles in gear at about 700-800 RPM for a couple of minutes and then looses RPM down to about 500 RPM and stalls. No problem running at 1000 -1200 RPM or higher.Compression is good, plugs are new and clean (but wet after stall), fuel pump is pumping, new fuel filter. Noticed a very slight (you can just barely feel it) pulsation in fuel line just before stall.<br /><br />I'm inclined to blame carbs. Do you agree? Is cleaning them enough?<br /><br />Need help fast! I'm supposed to take wife and mother-in-law for a trip to see tall ships in the habor this week.<br /><br />Thanks

 

[WillyBWright]

Re: Low speed stalling

Fuel pump. Especially if it's never been rebuilt. That originally had thin rubber check valves that pucker and leak. They made them out of thicker rubber as a fix, but they leak too, just not as bad. Now they're thin mylar and seem to be doing very well. Kits are cheap.

 

[Boston Habba]

Re: Low speed stalling

Thanks WillyB<br /><br />Now that i think about it, bad fuel pump check valves make sense. With the low vacum at idle, the check valves are not fully closing and that's why I can feel the pulse in the fuel line. Even if it's not the pump it is cheap and easy. I'll buy the parts tomorrow and let you know how it turns out.

 

[bshores]

Re: Low speed stalling

Boston Habba, I would love to know if the rebuilt fuel pump solves your problem. I am having the same difficulty with my 1989. If you wouldn't mind please post your results. <br /><br />Thanks.

 

[Boston Habba]

Re: Low speed stalling

Bought the rebuild kit today ($16). Only took about 30 minutes to do the job. Seems to have fixed the problem.