mercruiser 470 stalls going into gear when hot

[merc 470]

1980 merc 470 : stalls going into gear only when hot. has new carb, fuel pump & filter, fuel line cooler, new cap, rotor, plugs and coil, new impeller and thermostat, extra venting for engine cover, new intake & carb gaskets . Gear shift kill switch is not killing engine. Engine is not over 160 F. after long run. Lift cover for 10-15 minutes all is fine again. Points and timing are dead on. Carb has been adjusted by a few mechanics. When hot it starts to run rough and then stalls when idleing in gear. I am at my wit's end. I don't know what else to check or do.

 

[slimsilver1]

Re: mercruiser 470 stalls going into gear when hot

try getting rid of the points and condensor. they maybe losing spark when warm - switch to electronic ignition

 

[rodbolt]

Re: mercruiser 470 stalls going into gear when hot

check the ground of the plate the points mount on to the engine block. I have had a few on the 470 engines that the ground path had excessive resistance when hot and the engine would run poorly and stall.its not hard to add a ground wire if needed. the first one drove me nuts after that they got easier .<br /> which carb is this engine using ?

 

[MrBill]

Re: mercruiser 470 stalls going into gear when hot

Sounds like a short in the distributor...check lead exiting distributor for worn insulation around the metal clasp often put on it so it does not pull through. Also re-check cap for internal damage or crack, check very, very carefully. And same goes for rotor...

 

[hullofalottatrouble]

Re: mercruiser 470 stalls going into gear when hot

i know you said the fuel pump is new.. but have you tested? i know people so far seem to think its electrical.. but just curious if you have good fuel flow? tested pressure and vacuum on line?

 

[merc 470]

Re: mercruiser 470 stalls going into gear when hot

the carb is a rochester 2bbl from a carb remanufacturer. I still have the original merc carb that acted the same way. I will check that ground wire. the engine does always restart after it dies out, but will then stall as soon as shifted into gear. if it doesn't stall immediately, it will when giving it throttle and you can hear the carb sucking alot of air. if the throttle is pumped and you can get it to go, it seems to clear up until the next time you come down to idle or shut it down for a restart.

 

[hullofalottatrouble]

Re: mercruiser 470 stalls going into gear when hot

merc<br /><br />i would still consider looking at fuel flow. your latest post here seems to point to that to me.. but im not a marine mechanic or anything..

 

[merc 470]

Re: mercruiser 470 stalls going into gear when hot

in driveway there is good fuel flow, with finger there is vacuum on one side and pressure on the other. all lines were replaced to tank to insure that it was not sucking air.

 

[merc 470]

Re: mercruiser 470 stalls going into gear when hot

I always felt it was a fuel issue. In talking to mercruiser directly, and some of my local boat mechanics they said the vapor lock was common for these. that's why the fuel line cooler was installed and the extra venting put into the engine cover. the fuel line cooler was the mercruiser fix for vapor lock. the extra venting was the mercruiser dealer's idea and what he had done with other boats thwt he said were vapor locking.

 

[hullofalottatrouble]

Re: mercruiser 470 stalls going into gear when hot

merc.. still worth checking out with a pressure and vacuum gauge.. was the anti-siphon valve replaced as well? checked the pickup for any clogging etc?

 

[hullofalottatrouble]

Re: mercruiser 470 stalls going into gear when hot

okay.. i would guess that the dealer tested fuel flow before deciding on vapor lock.. good luck.. lots of smart people on here to help you..

 

[merc 470]

Re: mercruiser 470 stalls going into gear when hot

the tank is venting properly. Not a vacuum build up in tank. valve was not replaced, but was checked. it seemed ok. the tank was drained with electric pump and refilled with fresh gas. No gunk in tank.

 

[hullofalottatrouble]

Re: mercruiser 470 stalls going into gear when hot

merc,<br /><br />just curious.. how do the plugs look? they fouled up at all?

 

[brodie6]

Re: mercruiser 470 stalls going into gear when hot

I anxiously await the outcome of your problem as I am having the exact problem you are. I have a 1986 Mercruiser 140 and we have changed anything and everything on the boat. The problem remains. <br />Please keep us posted.

 

[Don S]

Re: mercruiser 470 stalls going into gear when hot

Could you discribe "have changed anything and everything on the boat". Did you check the upper and lower shift shaft in the pivot housing and drive to see if they were bent?<br />Thats just to start. When you have a problem, please don't just tack on to another post, start a new topic. That way those that read only the original post and answer won't cause all kinds of confusion as to who is answering what question. Besides after 6 months, I doubt if he is going to update and let anyone know if the problem was fixed or not, or even if he still owns the boat.

 

[Bt Doctur]

Re: mercruiser 470 stalls going into gear when hot

Sounds crazy, but try disconnecting the tach. lead at the dist.Had one years ago that did this in reverse only.Never found out why or the reason for it.

 

[Don S]

Re: mercruiser 470 stalls going into gear when hot

A shorted tach would affect all rpms, not just going into gear.<br /><br />He still needs to start a new thread to get the max amount of feedback.

 

[cosander]

Re: mercruiser 470 stalls going into gear when hot

http://www.breezeworks.net/cgi-bin/...ics.asp?ForumID=1&PagePosition=1&ThreadPage=1 <br /> use the search

 

[cosander]

Re: mercruiser 470 stalls going into gear when hot

It prolly your coil overheating. From what I have read on the other site.

 

[cosander]

Re: mercruiser 470 stalls going into gear when hot

http://www.breezeworks.net/cgi-bin/MBoard/forum/display_topic_threads.asp?ForumID=1&TopicID=62&SearchPagePosition=1&search=coil&searchMode=allwords&searchIn=Topic&forum=1&searchSor t=dateDESC&ReturnPage=Search