Mercury 200 hp fuel problems

natecollins1

Seaman Apprentice
Joined
Jun 30, 2006
Messages
37
Hi,

I am working on a 1984 200 hp V-6 Merc. The motor will only get up to about 4400 rpm, when the spec calls for 5300 - 5800 rpms. Compression is 125-130 on all cylinders. The fuel pump is supposed to have up to 5.5 psi at full throttle. I am noticing that the fuel pressure stays between 1-3 psi up to about 2000 rpm. With any higher rpm it is drop off back to 0-1 psi. I have rebuilt the fuel pump, checked the pulser line, and looked for fuel line restrictions. I am running 3/8" line to the motor cowling, 5/16" line to the fuel pump, and 5/16" line to the carb. Can you help resolve this issue?

Thanks
Nate
 

natecollins1

Seaman Apprentice
Joined
Jun 30, 2006
Messages
37
Re: Mercury 200 hp fuel problems

I also ran this motor with a seperate fuel tank hooked directly to the fuel pump. There was no change.
 

KCLOST

Commander
Joined
Jun 22, 2002
Messages
2,095
Re: Mercury 200 hp fuel problems

Check Spark!!!!! On all cylinders.....
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Mercury 200 hp fuel problems

Did this problem happen all of a sudden?
 

KCLOST

Commander
Joined
Jun 22, 2002
Messages
2,095
Re: Mercury 200 hp fuel problems

Less rpm less fuel pressure...
Easy check just to rule it out...
 

natecollins1

Seaman Apprentice
Joined
Jun 30, 2006
Messages
37
Re: Mercury 200 hp fuel problems

I have checked spark on all cylinders, checked each coil, checked the stator, and trigger. All are good. Checked each spark plug also. The ignition system checks out.
The fuel pump has new diaphragm kit, carbs have got the right jets in the right location, fuel lines inside the cowling have been replaced (no leaks), new fuel lines from the tank installed.

Or do I just need some Holy water and say a prayer?
 

phatmanmike

Captain
Joined
Oct 24, 2003
Messages
3,869
Re: Mercury 200 hp fuel problems

i had similar prob with my 1994 200hp. turns out the new stator i had just put on, well, it was just a smidgeon to small around and was restricting the timer base so it couldnt advance past 4400 rpms. it had just a lil too much plastic on it from when it was molded at factory.

hope this helps.

sometimes its stuff you just dont imagine!
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Mercury 200 hp fuel problems

Pump the primer bulb at WOT, if this increases you RPMs then your fuel pump is ailing. Trying hiting the choke and if this increases your RPMs then your carbs are dirty.

I'd check for spark @ WOT and make sure the timing is up to spec.
 

doug pARLETT

Recruit
Joined
Feb 16, 2010
Messages
1
Re: Mercury 200 hp fuel problems

I Have A 1999 200 Hp That Wont Start On Its Own If I Prime It It Will Fire This Motor Has No Choke But Has An Inrichment Valve It Has Good Blue Spark It Fires But Wont Stay Running I Just Put Motor On Boat And It Ran Great When I Looked At It And Bought It Now It Wont Run I Am A Motor Head I Guess Auto But Cant Figure This Out
 
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