Mercruiser 5.7L Hesitation

[realoldsalt]

I have a 1997 Bayliner with a 210hp 5.7L Alpha I that has been giving me problems. It runs good at idle but when put under load it has no power and will only rev to 3000 RPM. I found the distribator module was bad and replaced it,today I cleaned the carb and checked the float leavels ,and installed a new accellator pump. After warming it up with muffs on the trailer I tried to rev it up quickly and it would stop at around 3000, but when I took it up a little at a time it would reave all the way up.
Thanks for the number of the timing decal my dealer hadn't a clue that it existed.

 

[John_S]

Re: Mercruiser 5.7L Hesitation

Since you mentioned timing decal and you are new here, are you aware that to set the timing correctly, you have to set the Thunderbolt V in "base" mode, by grounding the purple/wht wire before starting?

 

[Bondo]

Re: Mercruiser 5.7L Hesitation

After warming it up with muffs on the trailer I tried to rev it up quickly and it would stop at around 3000, but when I took it up a little at a time it would reave all the way up.

Ayuh,... You Really shouldn't do that,.... It serves No useful purpose.....
'cause it's 'ell on the driveline.....

 

[realoldsalt]

Re: Mercruiser 5.7L Hesitation

Since you mentioned timing decal and you are new here, are you aware that to set the timing correctly, you have to set the Thunderbolt V in "base" mode, by grounding the purple/wht wire before starting?

Thats not a problem since this one is a thunderbolt IV.

 

[John_S]

Re: Mercruiser 5.7L Hesitation

I think, but would have to check, Merc switched to T5 in '95. It is possible to have a 2 year old engine/drive in a '97 boat. But first, lets go back a step, keying in on what Bondo said. After doing all the work you have only tested on the muffs? If so, do a load test on the water.

Don has a checklist on all the things to check for not obtaining correct wot rpms. Will need to search, but expect that it is in the "Adults Only" sticky thread.

http://forums.iboats.com/showthread.php?t=295070

 

[Polar_Bus]

Re: Mercruiser 5.7L Hesitation

Could also be old skank fuel....

 

[realoldsalt]

Re: Mercruiser 5.7L Hesitation

Since yesterday I did some checking of the fuel and I have some water in the tank. I put the required amout of dry gas and seafoam in the tank this morning hoping that will help.The distrubator only has the boaster module on it and no Knock sensor ,if it did I would suspect the knock sensor. The motor serial # is OF879866 I don't know if it is a 1996 or not I have no way to check it out. What do you guys think

 

[Bondo]

Re: Mercruiser 5.7L Hesitation

Since yesterday I did some checking of the fuel and I have some water in the tank. I put the required amout of dry gas and seafoam in the tank this morning hoping that will help.

Ayuh,... How about the fuel Filters,+ fuel Pump,..??
'ell you may have already pumped the carb full of it again, if you've been cranking it...

I'd pump the snot outta the bottom of the tank, rather than adding More alcohol to the fuel...

 

[John_S]

Re: Mercruiser 5.7L Hesitation

FWIW: The serial number shows on MercuryPartsExpress as having a Thunderbolt V system. Given it is a 5.7L/2brl, it will not have a knock sensor or knock module. It does require to be in "base" mode for timing.

http://www.mercurypartsexpress.com/us/index.php?target=my_machine_detail&mode=view&machine_id=239861

The pur/wht wire should be running along the starboard valve cover, by the intake manifold. It has a bullet connector end with rubber plug in it.

PS: get the water out first.