MerCruiser 5.7 starting problems

[cnadler3]

Hello everyone,

I have a 1996 Bayliner Capri 2050LS w/ a 5.7 MerCruiser, 2 barrel quadrajet carb, and alpha one gen 2 outdrive. When I bought the boat last year, it had problems starting cold. I would always have to use throttle only and give it gas to start it cold. Once the motor was warm, it would start ok without any gas.

However, the motor would sometimes bog down when accelerating and decelerating, also dying occasionally when decelerating. I spoke to my boat mechanic about it and he suggested rebuilding the carb. He stated that he thinks by looking at the carb that it had never been rebuilt and should make a noticeable difference in performance.

I picked up the boat and he said the carb was full of junk, but runs much better now. He bought the boat out and asked if I'd like to start it up on the muffs to hear and of course I did. Put the muffs on and didn't give it any gas, a single turn of the key and the engine fired right up. Turned it off and back on again, started like a brand new motor, very impressed.

I went to the lake this weekend and the first start was perfect. However, the next attempt to start the boat was pitiful. I turned the key and attempted to start with no luck. This is after running the boat for 15 minutes or so... I then used throttle only and was able to start it after about 10 seconds of moving the throttle back and forth while hold the key on.

The rest of the weekend consisted of tons of throttle only and starting after about 10 seconds of doing so. Once the boat is started, it runs perfect. I had a mechanic at the marina look at it and he adjusted the idle and adjustment screw and after doing so, the boat fired right up. However, the next start while on the lake was not successful.

Anyone have an idea what may cause intermittent starting after a carb rebuild? It is my understanding that the quadrajets aren't the easiest to rebuild, and obviously, something is not right. The boat now starts worse than before the carb rebuild, but runs much better once started.

Thanks,

Chris

 

[Bondo]

Re: MerCruiser 5.7 starting problems

Hello everyone,

I have a 1996 Bayliner Capri 2050LS w/ a 5.7 MerCruiser, 2 barrel quadrajet carb, and alpha one gen 2 outdrive. When I bought the boat last year, it had problems starting cold. I would always have to use throttle only and give it gas to start it cold. Once the motor was warm, it would start ok without any gas.

However, the motor would sometimes bog down when accelerating and decelerating, also dying occasionally when decelerating. I spoke to my boat mechanic about it and he suggested rebuilding the carb. He stated that he thinks by looking at the carb that it had never been rebuilt and should make a noticeable difference in performance.

I picked up the boat and he said the carb was full of junk, but runs much better now. He bought the boat out and asked if I'd like to start it up on the muffs to hear and of course I did. Put the muffs on and didn't give it any gas, a single turn of the key and the engine fired right up. Turned it off and back on again, started like a brand new motor, very impressed.

I went to the lake this weekend and the first start was perfect. However, the next attempt to start the boat was pitiful. I turned the key and attempted to start with no luck. This is after running the boat for 15 minutes or so... I then used throttle only and was able to start it after about 10 seconds of moving the throttle back and forth while hold the key on.

The rest of the weekend consisted of tons of throttle only and starting after about 10 seconds of doing so. Once the boat is started, it runs perfect. I had a mechanic at the marina look at it and he adjusted the idle and adjustment screw and after doing so, the boat fired right up. However, the next start while on the lake was not successful.

Anyone have an idea what may cause intermittent starting after a carb rebuild? It is my understanding that the quadrajets aren't the easiest to rebuild, and obviously, something is not right. The boat now starts worse than before the carb rebuild, but runs much better once started.

Thanks,

Chris

Ayuh,.... The Qudrajet is an old 4bbl. carb,.... Not what's on yer motor,...

Bein' a Carbed motor, addin' some throttle when startin' is Normal,...
It ain't Efi like yer car,...

That said,... Check the contents of the fuel filter,...
If the carb was full of Crap, I imagine the rest of the fuel system is boogered up as well,...
If so, the carb is probably full of crap, Again,...

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

Ayuh,.... The Qudrajet is an old 4bbl. carb,.... Not what's on yer motor,...

Bein' a Carbed motor, addin' some throttle when startin' is Normal,...
It ain't Efi like yer car,...

That said,... Check the contents of the fuel filter,...
If the carb was full of Crap, I imagine the rest of the fuel system is boogered up as well,...
If so, the carb is probably full of crap, Again,...

Bond-0,

Thanks for your reply. The mechanic initially said it was a 4bbl carb, but when I picked it up he said it is a 2bbl carb. Are all quadajet 4bbl? I understand the motor is carbureted, but I never had to give it gas before to start once the engine is warm. After the rebuild, I didn't give it any gas and it fired right up...

The fuel filter you speak of, is this the fuel water separator? If the fuel system is again boogered up, how is the best way to clean the entire system? What exactly should be replaced/cleaned to ensure the fuel system is clean from end to end?

Thanks,

Chris

 

[Bondo]

Re: MerCruiser 5.7 starting problems

Bond-0,

Thanks for your reply. The mechanic initially said it was a 4bbl carb, but when I picked it up he said it is a 2bbl carb. Are all quadajet 4bbl? I understand the motor is carbureted, but I never had to give it gas before to start once the engine is warm. After the rebuild, I didn't give it any gas and it fired right up...

The fuel filter you speak of, is this the fuel water separator? If the fuel system is again boogered up, how is the best way to clean the entire system? What exactly should be replaced/cleaned to ensure the fuel system is clean from end to end?

Thanks,

Chris

Ayuh,.... If a carb were a 2bbl., it Might be called a Twinjet,... Quad is 4 ain't it,..??

Quadrajet is an old Rochester carb, I'm guessin' ya got a Rochester 2bbl. carb,..

If there's crud in yer filter, that means there's crud in the tank,...
Start there,....

If it's ain't Tooo bad, a few filter changes might catch all the crud,...
If it's Really bad, tank replacement ain't outa the question,...

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

Ayuh,.... If a carb were a 2bbl., it Might be called a Twinjet,... Quad is 4 ain't it,..??

Quadrajet is an old Rochester carb, I'm guessin' ya got a Rochester 2bbl. carb,..

If there's crud in yer filter, that means there's crud in the tank,...
Start there,....

If it's ain't Tooo bad, a few filter changes might catch all the crud,...
If it's Really bad, tank replacement ain't outa the question,...

Bond-o,

I didn't see an answer to my original question about the fuel filter. Is there another fuel filter or just the fuel/water separator?

Thank you,

Chris

 

[Bondo]

Re: MerCruiser 5.7 starting problems

Bond-o,

I didn't see an answer to my original question about the fuel filter. Is there another fuel filter or just the fuel/water separator?

Thank you,

Chris

Ayuh,... I don't think there a filter in yer carb, but haven't put a hand on 1 in Years, 'n years,...

If there is, it's inside the inlet fittin',...

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

Ayuh,... I don't think there a filter in yer carb, but haven't put a hand on 1 in Years, 'n years,...

If there is, it's inside the inlet fittin',...

Bond-o,

I thought about what you said regarding a boogered up fuel system and doesn't make sense to me. If there was an issue with the fuel system and delivery, wouldn't the boat exhibit issues when accelerating and decelerating? Once the boat is started, it runs perfect, no hiccups. Prior to the rebuild, the boat bogged down sometimes under load. The rebuild definitely fixed the performance issues when running, but now has problems starting.

Thanks,

Chris

 

[Bondo]

Re: MerCruiser 5.7 starting problems

Bond-o,

I thought about what you said regarding a boogered up fuel system and doesn't make sense to me. If there was an issue with the fuel system and delivery, wouldn't the boat exhibit issues when accelerating and decelerating? Once the boat is started, it runs perfect, no hiccups. Prior to the rebuild, the boat bogged down sometimes under load. The rebuild definitely fixed the performance issues when running, but now has problems starting.

Thanks,

Chris

Ayuh,.... Basically, a carb has 3 separate, but intertwined circuits,....And a 4th function, the Choke...
'n of course the accelerator pump,..

There's idle, mid-range, 'n Wot,... It's All gotta work together, 'n at the right times,...

Have ya checked the Contents of the fuel filter yet,..??

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

Bond-o,

Yes, I checked the fuel/water separator and it is clean. One thing that I did not mention is that when the carb got rebuilt, the boat was actually in the shop for the second time for a shifting problem. I had an upper seal kit installed in the alpha one gen 2 and shortly thereafter, I started having problems going from forward to neutral and from neutral to reverse. I brought the boat to the mechanic and he stated he was able to replicate the shift problem, but adjusted the shifter cable on both sides and the problem was resolved.

However, my next trip to the lake was crappy because the shifting problem still existed. If the boat was in forward, I would put the shifter in neutral, but the boat would still be going forward. I would have to shut off the motor in order to get it in neutral and then into reverse. To say the least, I was very upset that the problem was not fixed.

I took the boat back to the mechanic and he stated that there is a shift interrupter switch that was not engaging that temporarily stalls the motor to allow the transmission to go from neutral to forward and vice versa. He stated they messed with the switch and was able to get it working. The boat now shifts ok, but not perfect....

I am taking the boat back in to the mechanic, only to have it fixed at no charge, since obviously the carb wasn’t installed successfully. I described the symptoms to him and he thinks either its running to rich or the gasket is too thin in between the carb and throttle body.

I was googling MerCruiser 5.7 warm starting problems and came across this posting:

http://www.boatersline.com/viewtopic.php?p=7263&sid=88a65f8e241457f9a29c466fee302456

This seems too coincidental.... Could the switch that was "fixed" be causing the boat not to start once it gets warm? The boat started perfect when cold, but has problems once it’s warm. I have also found numerous posts pointing to the coil causing similar issues.

PS: I am looking for a new boat mechanic!

Thanks,

Chris

 

[Bondo]

Re: MerCruiser 5.7 starting problems

Bond-o,

Yes, I checked the fuel/water separator and it is clean. One thing that I did not mention is that when the carb got rebuilt, the boat was actually in the shop for the second time for a shifting problem. I had an upper seal kit installed in the alpha one gen 2 and shortly thereafter, I started having problems going from forward to neutral and from neutral to reverse. I brought the boat to the mechanic and he stated he was able to replicate the shift problem, but adjusted the shifter cable on both sides and the problem was resolved.

However, my next trip to the lake was crappy because the shifting problem still existed. If the boat was in forward, I would put the shifter in neutral, but the boat would still be going forward. I would have to shut off the motor in order to get it in neutral and then into reverse. To say the least, I was very upset that the problem was not fixed.

I took the boat back to the mechanic and he stated that there is a shift interrupter switch that was not engaging that temporarily stalls the motor to allow the transmission to go from neutral to forward and vice versa. He stated they messed with the switch and was able to get it working. The boat now shifts ok, but not perfect....

I am taking the boat back in to the mechanic, only to have it fixed at no charge, since obviously the carb wasn’t installed successfully. I described the symptoms to him and he thinks either its running to rich or the gasket is too thin in between the carb and throttle body.

I was googling MerCruiser 5.7 warm starting problems and came across this posting:

View topic - 5.0/5.7 hard to start when hot at BoatersLine.com

This seems too coincidental.... Could the switch that was "fixed" be causing the boat not to start once it gets warm? The boat started perfect when cold, but has problems once it’s warm. I have also found numerous posts pointing to the coil causing similar issues.

PS: I am looking for a new boat mechanic!

Thanks,

Chris

Ayuh,.... Generally speakin',.... Any problems with the shift switch, are caused by a Bad lower shift cable,...

It should Only engage, killin' the spark, when comin' Outa gear, in the water,...

If the cable is mis-routed, or just plain Bad,.... It drags, holdin' the switch closed,...
So, Ya, it's possible,... maybe it only drags when warm,...

It Could be Alota things, but yer not the 1 doin' the Checkin',...

Right when it don't start, is it lackin' Fuel,..?? or Fire,..??

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

Ayuh,.... Generally speakin',.... Any problems with the shift switch, are caused by a Bad lower shift cable,...

It should Only engage, killin' the spark, when comin' Outa gear, in the water,...

If the cable is mis-routed, or just plain Bad,.... It drags, holdin' the switch closed,...
So, Ya, it's possible,... maybe it only drags when warm,...

It Could be Alota things, but yer not the 1 doin' the Checkin',...

Right when it don't start, is it lackin' Fuel,..?? or Fire,..??

I'm not sure how to tell what's lacking. I spoke to the mechanic and he seems to think it sounds like too much fuel. He thinks the idle may be too rich or something about the gasket between the carb and manifold being too thin causing the fuel to get too hot causing vapor issue.

I'll let you know what is done to hopefully permanently fix the boat. I've been trying to leave the boat at the lake, but it won't stay fixed long enough for that to happen.

Hopefully the mechanic can isolate the issue and finally fix the damn thing.

 

[Bondo]

Re: MerCruiser 5.7 starting problems

I'm not sure how to tell what's lacking. I spoke to the mechanic and he seems to think it sounds like too much fuel. He thinks the idle may be too rich or something about the gasket between the carb and manifold being too thin causing the fuel to get too hot causing vapor issue.

I'll let you know what is done to hopefully permanently fix the boat. I've been trying to leave the boat at the lake, but it won't stay fixed long enough for that to happen.

Hopefully the mechanic can isolate the issue and finally fix the damn thing.

Ayuh,... It involves removin' a few spark plugs, 'n Lookin' to see if their Sparkin', or Wet with fuel...

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

Ayuh,... It involves removin' a few spark plugs, 'n Lookin' to see if their Sparkin', or Wet with fuel...

I understand taking the spark plugs out to see if they're wet with fuel, but how do you tell if they're sparking if you take them out?

 

[NHGuy]

Re: MerCruiser 5.7 starting problems

You hold the plug's metal threaded end against the block for a ground, then crank the starter and check for spark.

 

[cnadler3]

Re: MerCruiser 5.7 starting problems

NH and Bond-o, thanks for the info. I took the boat back to the mechanic that rebuilt the carb and he offered to look at it for free. He told me he was unable to replicate the starting issue. He ran the boat on the hose for 15 minutes at 2500 rpms, turned it off, waited a few minutes, turned back on without a problem. He stated that he tested it over and over and everytime it started right up.

I mentioned to him that when it has problems starting, I could definitely smell fuel on the boat. He thinks the boat is either getting flooded or vapor locked, most likely vapor locked. He put a 3/8 inch gasket in between the carb and manifold and also adjusted the float.

I'm hoping that the gasket will fix the problem if it is a vapor lock issue and the float adjustment will fix the flooding problem if it is the cause. The last time I went to the lake, all 3 days it had problems starting, but he can't replicate the problem, bummer.

He told me that if it happens again, engage throttle only and open it all the way up for a few seconds, then try to start it. He said this should let a lot of air in to lean the motor out if it is flooded. I'm going to the lake this weekend for 3 days. If I experience the problem,
what can I do to determine if the engine is flooded or vapor locked? I have read some forums mentioning removing the spark arrestor to see if there is fuel dripping from it?

I will also check for spark has mentioned above. To do so, I just remove one spark plug, reconnect it back to the plug wire, hold it against the block for ground, and turn it over to see if I see spark? If there is spark, what next?