1989 3.7LX Starting Troubles

[wxkeep]

Started off the year with a tune-up - trying to find a little more hp for tubing, etc. So we installed new plugs (ngk), cables and rotor cap. Also cleaned the carb and ran some cleaner through the fuel tank. Installed an alternator (off to the side of the motor) so we put a new belt on the motor to run both the alternator and the power steering pump.

The motor has always been a bit tough to start. You sometimes have to pump the throttle arm. You almost always have to turn the key and let the motor try for a while before it wakes up. But then, once its ran for just a little while, it would always start instantly for the rest of the day. Now, however, it just doesn't like to start. You turn the key - the motor tries - but never fires. Well - it does - eventually - but if you stop the motor for even 3 minutes and try to start it again you ahve the same struggle getting it started.

We checked the fuel filter (clean), the compression (fine) and the fuel pump pressure (5psi). We did discover that the smaller of the two plates in the carb was loose - so we tightened them back up and it does seem to run a lot better now - once you get it started. We also discovered that there is a hose missing that runs from the carb to the engine. This hose has been missing since I bought the boat so, while I am sure it will help to have it, I am skeptical that it is the cause of my starting difficulty.

Any Ideas?

 

[wxkeep]

Re: 1989 3.7LX Starting Troubles

Any ideas at all? =/

 

[ErieRon]

Re: 1989 3.7LX Starting Troubles

Have you ever had the carb rebuilt? Cleaning it externally and just spraying carb cleaner in it doesn't do much. Sounds carb/choke related, but you need to check spark & fuel delivery too. If you haven't already, download manual No. 8 from this link below and look through the troubleshooting section.

http://www.4shared.com/dir/18247738/7a15ac6e/Mercruiser_Manuals.html

 

[sdoomaha]

Re: 1989 3.7LX Starting Troubles

"The motor has always been a bit tough to start. You sometimes have to pump the throttle arm. You almost always have to turn the key and let the motor try for a while before it wakes up. QUOTE"

Please take no offense, and I hate to state the obvious, but it is normal to have to pump the throttle on a carbed boat. Are you saying when you try to start it cold without pumping the throttle it is hard to start...but then after runnning a while a touch of the key will start it? That would be normal.

With my 470 if it sits more than a few days I have to continuously pump the throttle while trying to start it...and it normally take 2-3 tries, but after that it is good to go the rest of the day.

I'm sorry if i misunderstood your post...but I have helped folks at the boat ramp before that didn't realize that they had a way to throttle up the boat without putting it in gear...so I try not to overlook the obvious.

Good Luck.

 

[wxkeep]

Re: 1989 3.7LX Starting Troubles

I will download that manual and give it a look - thanks!!

As for the throttle pumping - yes that IS what I USED to do - have to pump it and it will start. And I agree - its normal to have to pump a cold motor (carb) that way. When I did - it would start fine the rest of the day. But NOW - you can pump it all you want and it takes forever to get it to start - like your'e trying to hit the magic "spot" on the throttle arm to get it to fire. You could then let it run for half an hour - shut it off - wait 2 minutes - and when you'd go to start it again - it would be like starting a cold motor again.