Motor Problem

[Treed1]

When I idle for 3 or 4 min. my motor acts like it runs out of gas,Check the bulb its soft, pump it up it runs fine. I replaced fuel line,bulb & coupling where fuel line hooks to motor. At times motor acts like 1 cylinder is not fireing until motor warms up. Went out this morning I have to keep RPM's up or motor quits check bulb it is very soft each time it happend.At high speed it felt like 1 cyl. was not firing. Top speed is around 53 today was lucky to get to 45.I have a 1989 Merc 150 XR4 HELP PLEASE!!

 

[wrechin2]

May be a fuel pump diaphram (spelling). Just had to replace one for rough idle, sag, and not turning rpms. If you pump the bulb will it ever get hard? If you pump it wait a few second and try again, does it have to pump back up? May actually be a electrical issue. Would be fairly easy to determine. There is high and low voltage from the stator and it switches over around 3K rpm. It acts like running out of fuel. I had one that was running on 5 cylinder untill it ran for about 3 minutes and you could watch it pick up. PRAY that you don't have a stator bad. Those are VERY expensive, if it has the early style 40 amp with only 2 wires. I have a test one for ignition as the charging side is bad. Most of the time I conver to a 9 or 16 amp sytem for ALOT less. It also depends on how much stuff you have running. Could also be a mechanical issue on one of the 2 cylinders that "pulses" the fuel pump diaphram.

 

[Guest]

Sounds like your fuel pump is going out. probably has a hole in the diaphram. Does your bulb ever pump up hard? The cyl not running is probably from fuel dumping in from bad diaphram.

 

[Treed1]

When you pump the bulb up it will get hard. Up until today it would stay pumped up unless I Idled for a 100 yards or so.. I'm not a mechanic but I am leaning more towards the fuel pump. My Uncle had a stator go out on his boat, His acted totally different than the problem I have. Is it hard to change the diaphram? THANKS for all the help!!!

 

[wrechin2]

No, it is pretty simple. I had to change one tuesday on ditchdocs that had split and had a 1 inch gash in it. It was flooding 1 cylinder and quit totally, due to no fuel was moving, while he was fishing TX. He had to bypass the pump and have his partner pump it to get back to weigh in. Stators can act like running out fuel, but with the bulb issue, it may just be that simple. To know for sure. is it taking several pumps (defanate fuel issue) to re-prime the system or half a pump (not a fuel issue) and it is firm?

 

[Treed1]

Several pumps 8 to 10 before it gets hard. I talked to my uncle he has replaced fuel pumps before says it not hard. Can you get a kit and rebuild or do you have to by a new fuel pump.

 

[wrechin2]

It is defanatly a fuel issue. You buy just repair kits. You can have 2 different pumps. Square or rectangled. If yours is all factory then it should have a squared pump and the kit # is 21-857005A1 and will be around $21 and will come instructions and everything servicable inside. I ran into 1 that someone had a different year intake on it. It is at the bottom close to the starter and the carbs to look. I ran into a issue similar to it and it was trash in the tank would get on the pick up and the fuel pump would suck the line dry then when the engine would quit, the trash would fall away and it would allow it to pump up. It is more than likely a ruptured diaphram given the 1 cylinder misfiring as it takes 2 clinders to "pulse" the pump and with a hole in one diaphram, it is going into that 1 cylinder and flooding it out and when you prime it, the one cylinder is getting flooded from the get go and was clearing up and now it isn't.

 

[Treed1]

Thanks again for all your help. emoWorthy It is the square pump,I will order parts Mon. or tue. Will someone have them in stock? Maybe Nichols?

 

[wrechin2]

Probably, it is a VERY common part.

 

[Treed1]

Wrechin2 You are DA MAN! Took fuel pump apart found 3/4 in tare in diphram also found the round rubber peace's inside fuel pump one of them was pulled inside itself with a small tare. I don't know how motor was running at all. I hope all the rubber comes in kit. Front,Rear & 2 round ones. Thanks again!!!!! I will let you know if this fixes it. emoSmile

 

[wrechin2]

The kit comes with both rubber diaprams, both gaskets, 2 new check valves (the clear pieces in the center body) and the pins that hold them in, both new springs and the caps on top of the springs. EVERYTHING is replaced except for the hard aluminum pieces.

 

[Treed1]

Picked up the fuel pump kit today,Had it on the motor in about 45 min. motor runs GREAT. I have not had it on the water but it will idle at the house & it would not do that on the lake. You helped a poor old man out THANKS AGAIN!!!! emoToast emoWorthy emoWorthy emoWorthy emoThanks

 

[wrechin2]

Pretty simple wasn't it. Directions and all.

 

[jo jo]

Just had the same prob, fuel pump kit around 20 bucks solved my probs.