1989 70hp evinrude wont idle or stay running.

[Johnnyfairplay]

I've been working on troubleshooting our 1989 70hp evinrude E70TLCEM for a while now an am looking for any assistance or advice. This engine will not idle or stay running for more than 5 seconds. This is a total 180 because the engine was working fine and seemed to have nothing wrong with it since we owned it. The engine was bought second hand so it is new to us and we have little knowledge of its history. VRO has been removed prior to us owning it. Compression on all 3 cylinders is between 79 and 80 psi...this seemed low to me however, when the motor ran, it ran fine. Motor has brand new impeller, power pack, and starter solinoid. Motor is on a 15ft mfg deep-v and topped out at 36mph when it ran. In the process of trouble shooting the following has been done to the motor: carburetors soaked cleaned and rebuilt, correct jets installed, fuel pump replaced, fuel filter replaced, fuel and pulse lines replaced. I know the engine is getting spark on all 3 cylinders and it's getting gas to the carburetors. The primer solinoid works however it's reading at 7.8 ohms(does this have anything to do with keeping the engine from idling?) I'm starting to think there is a compression issue with this motor. Tomorrow I am going to get another compression test done on it and check out the intake reeds.

Background:

This engine seemed to run great out of water and has ran fine for hours on the lake the hand full of times we have taken it out. other then two incidents where it had stranded us after getting us out on the water. The first time this engine stranded us it would not start for anything and seemed to be flooded because it would leak gas. We seafoamed the engine chalking it up to be gummed up carbs, pistons or user error. This seemed to have fixed our issues because the engine ran like a top for several trips after that. The next time it stranded us it did the same thing however this trip it seemed like the engine wasn't getting any fuel. After messing with the fuel lines we did end up getting it to turn over and ripped it to the marina. About half way the engine lost all power and died again. It hasn't ran since, besides 2 times we got it to idle fine but would not do it again after. When we got home we diagnosed it as a fuel delivery problem. However, after going through all the fuel lines, fuel pump and all three carburetors, it still wont run for more the 5 seconds and wont even do that consistently if at all. The engine will crank a few time if you choke the **** out of it but wont go, it's like it's not getting gas even though there is no reason it shouldn't be. We did get the motor to run fine once or twice since it's been out of the water but all that was done was the fuel pump pulse limiter line was shortened because when the new lines were ran it was cut a bit long. This fixed all issues for a solid 20 mins before dieing out again. I am stumped because this motor ran fine and one day just wont keep idle, it is very inconsistent and nothing seems to be leading us down any paths, nothing else we try really consistently makes a difference. Any ideas? Thanks.

 

[flyingscott]

Re-check the compression and then do a spark test. If that is truly your compression your motor has serious issues. Which way is the red lever pointing on the primer solenoid?

 

[Johnnyfairplay]

i just took the primer solenoid apart the other day, cleaned the terminals and checked the top gaskets. I've never messed with the lever until the motor started having problems, basically it wont turn over at all while its in the run position. if i pump up the ball and flip the lever to the choke position it seems to dump enough gas in it to cough a few times before dying out.

 

[Johnnyfairplay]

I am going to recheck the compression and get back to you. Im positive there is spark because its been confirmed with two testers and different people testing it. wires seem old could spark being weak be a thing? Like i said when the motor was purchased the compression was a very even 79ish psi on all 3 cylinders. I have been told that these loopers tend to run a little lower psi and have been told by a tech that they can run low as long as they are even. I've always thought this was a little too low but the motor ran great. i'm a bit puzzled because there has also been no gradual loss of power or anything like that its just a night and day change. Will re-test and update.

 

[jakedaawg]

Did the little rollers on the timing cam and throttle cam disintegrate? Should be two layers, Inner black plastic and outer translucent.