2002 Mercury 150XL S/N 0T494104 - Motor RPM will not exceed 1500 RPM

[lewisd@optonline.net]

Good Morning all - Need some help - I have a 2002 Mercury 150XL S/N 0T494104 and its running poorly. I changed the Plugs, Fuel Lines, Water Separator body & Filter, and Fuel Bulb. The motors started fine when cold. When I took the boat out yesterday, I still noticed a changing (varying) of RPM's when on plane. Maybe a better word is the Motor Surges (loosing RPM & increasing RPM by itself RANDOMLY) I ran it about an hour and it happened 5 or 6 times. I thought it was getting better when all of a sudden RPM dropped dramatically to about 1500. I was able to limp to a dock and shut the motor down.

It was hard to start after sitting which was the situation I was trying to correct by changing the parts above. It would start but I couldn't put it in gear without it stalling. It would run up to 1500 RPM (Tops) without being in gear at almost full throttle. Its stalled anytime under 1000 RPM.

I got it towed to a marina who is now working on it. Does anyone have any suggestions??

I purchased the Pulse Fuel Pump parts and Thermostats but they haven't arrived yet.

I appreciate everyone's thoughts!

Best Regards - Dave

[leonreno]

Fuel pump kit is a good idea, also should check compression first. Then check spark with a spark gap tester or a timing light. I believe your motor is a carburetor motor, they should probably be cleaned and needle floats checked and new gasket kits put in.

and since you replace fuel filter and bulb did you check the fuel lines? https://www.bbcboards.net/showthread.php?t=22490

[EuropeanAM]

Dave- am I possibly helping you through PM's, email, and now a post here?

[lewisd@optonline.net]

Don - Yes you are. The marina working on the boat is changing the diaphragm in the fuel pump. Thank you very much.

[lewisd@optonline.net]

Thank you - The marina working on the boat reported last night that the fuel pump needed to be rebuilt. They are doing that this morning! Thank you all!!

[EuropeanAM]

Awesome. Be sure to report back here after finished with results.

[lewisd@optonline.net]

Good Morning All - My problem is fixed. There are (2) fixes to report. 1. The diaphragm in the Pulse Fuel Pump was bad and wouldn't give the motor enough fuel to run over 1500 RPM. 2. The hard to start issue when hot was caused by a BAD second Water Separator that was installed under the deck. In fact, it was so bad that it was leaking small amounts of fuel and introducing air in the fuel system. See picture
[IMG]file:///C:/Users/lewis08/AppData/Local/Temp/1/msohtmlclip1/01/clip_image001.jpg[/IMG] It was amazing that the boat ran at all.. After 2 sea trials it seems to run great now.

Thank you to everyone you helped me. I really appreciate it. - Dave

[EuropeanAM]

Unfortunately we can't see the picture since you referenced a file on your hard drive, rather than uploading it via the "picture-frame button" in the menu-bar portion of the Quick Reply window.

Glad to hear you got everything fixed!