Hard starting when hot - 1998 Yamaha 225's

[jensal1]

Both engines start fine from cold and run well anywhere from idle to cruise through full throttle. However, after they're fully warmed up and are shut down for say 20 minutes restarting is a challenge. The symptom is that they restart right away but quickly stall. After using the electric primer pump a few seconds they'll start but again quickly stall. This may have to be repeated 10 times and then they seem to be fine. The problem seems to be somewhat worse on the port side engine. I suspect it's a running-out-of-fuel situation, similar to vapor lock. This seems to have gotten worse with time, that is no problem in the 2010 summer, then it showed up a little in 2011 and a little more now in 2012. If fuel filters were an issue I'd expect problems at higher speeds and it seems to run fine there. I use Stabil, Yamaha Ring Free, and ethanol enzyme fuel treatments. The boat is a 1998 GW Sailfish 272.

Does anybody have any suggestions where to look? :hmm

 

[Tucker]

Jen, when was the last time the low pressure fuel pumps where changed. Sounds like that's the problem. Should be done about ever 3-4 years. Assuming you have the OX66 225HP; the big blocks are pretty hard on fuel pumps. You have 3-per engine and the cost about $40 each. To confirm they're good or bad unbolt all three pumps but leave hose connections in place. Have someone hit the primer button while you are looking for fuel leaking from the back of the pumps. Good Luck!!

 

[ahill]

My son replaced the lp pumps on his '99 250 and at low rpms it shuts off. Above 650 rpms in gear its fine.
Any suggestions?

 

[megabytes]

Not sure if this applies but there was a run of defective fuel hose around this time. My 1997 272 was affected. It only showed for the first time on a hot summer day. The hose would constrict and starve the engine. All hoses were replaced by the builder and paid by the hose manufacturer.
Pursuits, GW, and a few other brands had the defective lines.

Your problem may be unrelated but it wouldn't hurt to check with GW to see if you hull number had the bad hose and if it was replaced. The fact that both engines see the issue sure sounds like this may be the cause.

 

[jensal1]

I appreciate the suggestions. Once I get a chance to check it out I'll let you know what I find. Thanks!

 

[Tucker]

Intersting about the hose meg. Assuming you mean the 3/8" supply hoses. Here in Maryland, we've had ethanol fuel for about 10-years. I'm always eye-balling my lines and squeezing them. I've also replace some lines because of modifications, etc. I can say the new 3/8" fuel line is much small on the OD than the OEM stuff Grady used. Not sure why; they both have the same CC designation but the new stuff has a later revision. I used the standard issue hose from West Marine, believe Shields is the mfgr. Do you recall who made the hose that was defective?
Ahill, those engines are suppose to idle between 650-700 RPM's. Also sounds like he may have to sync & link his throttle linkage and check the TPS. Not hard to do but the procedure needs to done in the correct sequence. The TPS, throttle linkage, and oil pump linkage are spring loaded and all tied together; doesn't take much to loosen things. Good thing is no parts are required other than the TPS test cable which is under $40 I believe. He'll also need a DVA adapter for his multimeter. I got mine off the internet for about $30 and is required for testing just about anything electrical on these Yamaha's. What shop manual does he have?
Jen please be sure to let us know the verdict...

 

[jensal1]

Tucker,
I just checked the three low pressure fuel pumps on the port engine. The lower of the three clearly leaks when the primer pump is activated. I ordered three new pumps from "boats.net" at $37.50 each. Once I get them installed I'll post the results. Since this appears to be a clear issue, hopefully I won't have to change out fuel lines. . . . one step at a time! Thanks! -Mark (Jensal is my 'code' name based on combining my three daughter's names!)

 

[megabytes]

IIRC the company was barrier, GW customer service will know. I knew of several boats in the Wilmington area affected.

 

[jensal1]

After checking the port motor fuel pumps and finding one leaking I replaced all three pumps on that engine, as per Tucker's suggestion. After running earlier today, shutting down and then restarting after maybe a half hour, the port motor restarted and kept running with no problem. I didn't touch the starboard motor and it was a hard start. I just checked the starboard motor pumps now to see if any were leaking when dismounted, but no leaks were found. Considering the success with the port motor, I'm going to replace the three on the starboard motor asap. I'll post the results of that repair when done. Thanks again for the help.

 

[seasick]

My son replaced the lp pumps on his '99 250 and at low rpms it shuts off. Above 650 rpms in gear its fine.
Any suggestions?

What do you consider a ow idle. It should be about 730 rpm

 

[jensal1]

The idle specification for 1998 225 OX66's is 700rpm +/- 25rpm.

 

[family affair]

One of mine didn't leak. I took the pump apart anyway and had a 1/2" tear in the diaphragm. I still cannot figure that one out. Needless to say the engine ran much better after that find!