1992 4.3lx starting problems

[jonih]

hello all,

boat info...1992 merc 4.3 LX

Back again, still can't get my 92 Merc to start. It turns over, but will not start. Before, it seemed it was getting way too much gas, so fixed the floats and now it seems it is getting no gas....
So far I have done the following.

replaced...starter, altinator, fuel filter, rebuilt carb, checked and replaced a fuse that was bad and replaced the fuel filter. It now apears the 2nd fuel filter has gone bad or is not pumping fuel, It will click but not hum even when checking with it straight to the battery. Does anyone have any idea what would make two brand new fuel filters go bad? Any ideas would be helpful.

Rayh

 

[Don S]

Re: 1992 4.3lx starting problems

Do you have spark?

 

[jonih]

Re: 1992 4.3lx starting problems

yes, I put a small amount of gas into carb, it started...but then it died. I can't understand how 2 brand new fuel pumps can go bad or what may cause that to happen.

 

[180shabah]

Re: 1992 4.3lx starting problems

Perhaps the new pump was defective, doubt it but possible.

What is the condition of your fuel, Is there a lot of trash in the tank.

 

[jonih]

Re: 1992 4.3lx starting problems

this is the 2nd brand new pump in one month..we got one, seemed it just stopped working...of course, they would not exchange it so we bought a new one. We checked the fuel and it looks find..no junk in it...we replaced the old fuel pump with a new water separator one.

We cant figure out what would cause a new fuel pump to go bad, or if there is some fuse or something that would keep it from running. We took the hose off, tried to get it to pump into a bucket...nothing doin...hate to spend another 200+ if it is something in the wiring or something that is causing them to go bad..we have not been able to run the boat with either pump so it isn't like it should have worn out...

 

[jonih]

Re: 1992 4.3lx starting problems

sorry that should have been a new fuel filter with water separator...

 

[Don S]

Re: 1992 4.3lx starting problems

We cant figure out what would cause a new fuel pump to go bad, or if there is some fuse or something that would keep it from running. We took the hose off, tried to get it to pump into a bucket...nothing doin...hate to spend another 200+ if it is something in the wiring or something that is causing them to go bad..

I think it's time to tell us what kind of setup you actually have.
A 92 Merc 4.3LX had a mechanical fuel pump. No wires, no fuses.

 

[jonih]

Re: 1992 4.3lx starting problems

the boat is a 1992 Larson 4.3 LX with a mercruiser inboard (it is a GM Motor) it had an electric fuel pump and a regular fuel filter, we replaced it with a brand new fuel pump and a new fuel filter with water separator. Got the fuel pump at the marine parts store it is the one listed for this engine, and it didn't work..rebuilt carb, replaced everything else, still didn't work..replaced it again...new one not working...

 

[jonih]

Re: 1992 4.3lx starting problems

sorry I may not be saying all this right...hubby dictating as he works on boat

 

[Don S]

Re: 1992 4.3lx starting problems

It's very hard to troubleshoot an engine over the internet. It's even harder when someone else is doing the work and someone else is trying to explain it.
Then factor in that the engine never had an electric fuel pump, yours does, so it's aftermarket or something. Now no-one knows how it's wired, plumbed or anything else. Totally impossible to say what the problem is.
Going to need some pictures of the pump and a discription of how it wired in to even make a guess what the problem is.

 

[jonih]

Re: 1992 4.3lx starting problems

not sure....but when we go to different marine part websites, and put in the engine serial number, it shows an electric fuel pump as stock on this model engine. At the Marine part store, when we give them the year make and model, they show this electric fuel pump..however...when we go to Larson website, it does not even show a 1992 180 SEI (which is what the side of the boat says) only shows 93 and up ...not sure what that means but for some reason, this engine came stock with electric fuel pump and everywhere we checked shows this fuel pump as stock not a replacement part.

 

[Don S]

Re: 1992 4.3lx starting problems

You haven't posted a SN, but it would sure help if you did. It doesn't , matter what the boat is, only the engine and drive.

 

[jonih]

Re: 1992 4.3lx starting problems

This is the serial number, OD822750

 

[Don S]

Re: 1992 4.3lx starting problems

SN break in 92, didn't notice that before. That is why with Mercruiser, you do things by SN, year means nothing.

On the port side of the engine, just above the block oil filter boss, is an oil pressure switch that controls the fuel pump. It gets power from 2 places.
Look at the drawing. Since you changed the starter, did you hook up the wire for going to the starter? Did the starter have the proper terminal?
Here is a wiring diagram of the fuel pump system.

 

[jonih]

Re: 1992 4.3lx starting problems

thank you so much....we will replace the oil pressure switch this week and see what happens (parts place is closed now)...one last thing however....if I unhook the fuel pump electrical connection and run a wire from the battery to the fuel pump...shouldn't it at least run (hum) even if the oil pressure switch is bad?

 

[Don S]

Re: 1992 4.3lx starting problems

we will replace the oil pressure switch this week and see what happens

STOP changing parts till you know what is wrong.
Why change the pressure switch? If it won't start while cranking, then it has nothing to do with the pressure switch.
Has it ever started corrctly? What happened just before it started NOT STARTING?
Any repairs, what was done? Is this a new boat to you that didn't work before you got it??????

 

[180shabah]

Re: 1992 4.3lx starting problems

......if I unhook the fuel pump electrical connection and run a wire from the battery to the fuel pump...shouldn't it at least run (hum) even if the oil pressure switch is bad?

Needs two wires, positive and negative, but yes it should run.

 

[jonih]

Re: 1992 4.3lx starting problems

got the 1992 Larson 18' boat that sat for 2 years, it ran rough and would not idle so I had the carb gasket replaced. Had new starter and weber 4 barrel carb rebuilt rebuilt 2 months ago and it ran fine (this was done by a marine mechanic in Florida), but storm beached it in Florida, had a lot of water on board, got it back home and it ran fine, then battery died, alternator not charging - replaced alternator (which looked corroded from beaching and sea water in Florida I believe), wouldn't start - electric in line fuel pump did not pump (no noise or hum when turned on) replaced fuel pump, took the boat out and it ran fine, next time out it idled rough and would die out under throttle, then would not start, did not seem to get gas - electric in line fuel pump did not pump (no noise or hum when turned on) replaced it again (I could definitely hear fuel pump). It ran rough so I adjusted the carb, well tried too. Last time out it ran rough but I tried it anyway, didn't get far, I had to hold the choke closed by hand on the carb so we could limp back to the dock, didnt want to run, and seemed to have too much gas in carb - I looked in carb body and saw gas pudddling in the back, rebuilt the carb, step by step from a service manual, engine turns over but won't start......unless I pour some gas in the carb, then it starts and then dies out. I appreciate any help you can give me.

 

[DHPMARINE]

Re: 1992 4.3lx starting problems

I have had problems with electric fuel pumps not being able to pull through an empty (new) water separater.At our shop we fill the new filter with gas before installing.Solves a lot of headaches.

DHP

 

[jonih]

Re: 1992 4.3lx starting problems

Thanks, I know the pump was working because after I put it on and rebuilt the carb, I pulled the carb off for adjustments and it was full of gas