89 mercruiser 3.0 won't start after warmup

[searay89]

Hi -<br />I have a 89 3.0 mercuiser. Start great, runs perfect for 1/2 hour or so then starts to bog under load. Will idle OK but need to limp in. If I turn it off it will not start again. After a cool down period (1/2 hour) It will be OK again. Temp gauge always reads about 150 deg.<br /><br />Have replaced the following - carb, points (replaced with electronic module), plugs, wires, coil, dist cap. Adjusted the timing.<br /><br />HELP!<br />Thanks..

 

[Bondo]

Re: 89 mercruiser 3.0 won't start after warmup

Your engine is Starving for Fuel...........<br />Look for a Restriction in the Fuel Delivery........

 

[searay89]

Re: 89 mercruiser 3.0 won't start after warmup

Looking in the carb I can see fuel squirting in when I pump the throttle. Seems to be getting fuel.

 

[affa]

Re: 89 mercruiser 3.0 won't start after warmup

Hi<br />Have you adjusted the choke?<br />Regards<br />Affa

 

[searay89]

Re: 89 mercruiser 3.0 won't start after warmup

Hi Affa,<br /><br />Thanks for the reply -<br />Before I replaced the carb, the old carb had bad choke (electronic) so I just opened it up and unhooked the wire - boat started/ran fine without choke. Since the new carb came with new choke I am using choke again, it is adjusted properly - problem happened with old and new setup.

 

[hoot]

Re: 89 mercruiser 3.0 won't start after warmup

since you are getting fuel, i would be looking at ignition. heat breaks down electronic components. measure volts at + post of coil while running good and then when problem occurs, alternator output also. could be coil resistor going bad. put points/condensor back in and try it. check resistance of coil from + to - and + to secondary post. and check fuel vent line to be sure it is open.

 

[searay89]

Re: 89 mercruiser 3.0 won't start after warmup

Thanks,<br /><br />Have already tried putting points back in - same problem. The schematic shows the resistive wire from ignition switch to coil. This could be bad i'll check but this wire is bypassed when starting (there's a wire direct from starter). <br /><br />I'll check the fuel vent line - this seems difficult to get to?

 

[hoot]

Re: 89 mercruiser 3.0 won't start after warmup

you can run a wire directly from the battery to the + post and see what happens, but don't leave it on long. i haven't seen many post where the resistor wire has gone bad. i have 7.5 volts on my + post with the key on. usually the vent itself is the thing that gets clogged either from wax or dirt dobbers. you can remove gas cap next time this happens and listen for a slight whoosh sound if you are not venting. i don't have my manual and need some help on this, but is the accelerator pump circuit and the normal running/start circuit in carb the same? going back to bondo's posts, does fuel squirting in from the pump mean fuel is getting in during normal running of the motor? check fuel filters also.

 

[Rhadley]

Re: 89 mercruiser 3.0 won't start after warmup

I have read where there is often a vapor lock problem if temperature around the engine gets too high. Try openning the engine cover when it doesn't start to see if that lets it start. If so, you may just have too much heat there. Run the blower all the time and maybe add better ventalation. 2nd blower? Are vent hoses twisted?

 

[orrismic]

Re: 89 mercruiser 3.0 won't start after warmup

I just read something in a magazine about this a couple of weeks ago. Said to get a new better battery. I'll go see if I can find it...<br /><br />M

 

[orrismic]

Re: 89 mercruiser 3.0 won't start after warmup

Here it is from my clymer manual:<br /><br />The engine starts fine when cold and restarts easily when used for short distance boating. After a trip of longer duration, however, the starter will not crank and restart the hot engine. After the engine cools for 1-3 hours the starter works normally. An open-circuit test and hydrometer check of the battery indicates that it is in satisfactory condition.<br /> Disregard helpful hints about resetting the ignition timing or mechanics who tell you that this is a typical of chevrolet or Ford marine engines. The key here is your battery, especially if it has been replaced recently. Check the cold cranking amerage rating of the battery installed in the vehicle and compare it to specs. If a replacement battery has been installed, the odds are high that whele the battery has sufficient power for a cold start, it is insufficient to cope with the high internal resistance in the starter and reduced engine operating tolerances which result fromn engine operation , especially in extremely warm weather.<br /><br />Manty owners buy a replacemnet battery according to the length of the guarantee and their pocket book. While a 12-month battery seems satisfactory (and the price is right) it does not have the power and stamina to handle the starting requirements of your engine.<br /><br />.... have you replaced the battery lately?

 

[searay89]

Re: 89 mercruiser 3.0 won't start after warmup

Thanks for all of the suggestions - I'm leaning toward vapor lock but will also check voltage on the coil etc. I have new fuel filter in hand. The battery is brand new - first use was last weekend.<br /><br />This problem first happened at end of last season and all of this year. One thing in common is that I have refueled at the same station the past 3 times. Previously I had never used this brand of gas.<br /><br />Is there an additive difference in brands that might cause the fuel to boil at a lower temp in some brands?

 

[affa]

Re: 89 mercruiser 3.0 won't start after warmup

Hi again<br />To check if its vapor lock, you can put a hand pump on the fuel line to see if it starts when you get fuel pressure.<br />Regards<br />Affa

 

[searay89]

Re: 89 mercruiser 3.0 won't start after warmup

I would like to close out this post.<br /><br />Thanks to everyone who made suggestions.<br /><br />This was not an easy problem and cost me much time and money (carb, ignition, fuel line, filters, etc).<br /><br />I have now used the boat for two days with no issues. The problem appears to be the brand of gasoline I was using! I am located in the northeast. There is a brand of gas that seems somewhat local - there are only 2 stations near me - I think this brand is more common in PA. I refueled near my house exculsively at one station since last fall (4 times total). It appears that this brand has some type of additive that causes the fuel to vaporize at a lower temp than other brands. Obviously this engine is right on the edge of vapor lock - this brand really puts it over the edge.<br /><br />HESS - stay away from this fuel at all cost.

 

[dcpcccrc]

Re: 89 mercruiser 3.0 won't start after warmup

after you shut down the engine the fuel that is sitting in the carb starts to boil thats why after a half hour it starts again