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Mercruiser 888 running problems

J

Jessie00721

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"Hello, I am currently having

"Hello, I am currently having some runnning problems with my mercruiser 888 engine. At first it only wants to go half the speed. When running right it does 30mph and now I only get 15mph out of it. Been messing around all day with this, did find water in the fuel so I drained the tank, new water seperater and cleaned the carb about 7 times today, still no improvement. Last time checking it, the boat would not stay running in gear. Gave up for today? Any ideas on what to check? Just so you know, it idels nice and rev's good in nuetral, seems to have a problem under load. I have not used it this year, only put it in the water and it has been sitting ever since.

Last year I replaced everything in the lower unit, heads, plugs, oil, distributer button.

This year: New starter and gimbal bearing.

Any ideas on what to check or retry would be great, kind of at a point where I dont know what to check.

Thanks,
Jessie"
 
"Fuel system ( fuel inject

"Fuel system ( fuel injection or carbuerator)? Ignition ( points, electronic distributor, or coil pack)? Does it misfire accellerating or at open throttle?"
 
"Fuel system is carb. Ignitio

"Fuel system is carb. Ignition is points. It was not misfiring, just loss of power. Now I believe it will not stay running in gear? Another guy took it out and got towed back in so he said he could not keep it running. Even if it stayed running only would get 1/2 power but seemed steady most of the time. Once when testing it died down slowly but that was before cleaning out the water. Dristributor is a mallory if you need to know that to.

Thanks,
Jessie"
 
Put in and gap new set of poin

Put in and gap new set of points. What engine size (displacement)?
 
"Ford 302 V-8, OK, try the new

"Ford 302 V-8, OK, try the new points and see what happens. Note what happens when you gun it and at full trottle, in gear, in the water."
 
"I tried so many times today I

"I tried so many times today I am trying to remember, I think different things happend. Sometimes it will just go right to open throttle and run half the speed it should and sometimes it would die right out if you tried to gun it. When that happend you had to slowly take it up to speed.

thanks again for all the input so far!"
 
"Sounds like the carb is not f

"Sounds like the carb is not functioning correctly in several ways (and I know it's been massaged). Can you try another carb, or get a rebuilt one?

Jeff"
 
"Sounds to me like the distrib

"Sounds to me like the distributor is not advancing. Look for unhooked/cracked/hole in vacuum line. No advance will cause those exact problems, the fact that it only happens under load is a dead giveaway. Easy fix and CHEAP."
 
"Pulled the carb off again and

"Pulled the carb off again and did a really good check cleaning. Found 1 chech ball in the carb to the accelerator pump missing. Put it all back together and runs good with the exception of it only doing about 18 mph instead of 30. But no stalling so I guess that fixed one problem. I will try checking the distributor next for what was said. I dont really understand how the advance works on a distributor so if anyone could let me know the basics it would be great.

Thanks,
Jessie"
 
"looked at the distributor qui

"looked at the distributor quickly, no vacuum line installed, it does have a threaded hole but nothing is there, nothing was ever there and it ran fine before? Anyhow, it is a Mallory Model YL

Jessie"
 
"Could be mechanical advance i

"Could be mechanical advance instead of vacuum. Weights could be stuck. If you just had the cap off for a new rotor, then take it off again, and look at whats underneath, make sure the weights and or springs are functioning normally."
 
"I can double check, when I ha

"I can double check, when I had it off I did poke a screwdriver through some opening in the plate and could move the mechanisms underneath and they spung back into place."
 
"Jesse:

Vacuum advances are

"Jesse:

Vacuum advances are not used on marine engines, and would not have a thing to do with your problem in any case.

It is very possible the mechanical advance is not advancing due to rust or whatever. The best way to tell for sure is with a timing light. Let it idle, then slowly take her up to about 3,000 rpms. The timing mark should move about an inch. If not, that's the next problem to resolve.

Jeff"
 
"Checked the plugs today, all

"Checked the plugs today, all was good except one was wet so I replaced that plug and tested it again. Did about 19mph after that, still about 10mph short of what I am looking for. I did have some barnacle build up so I got in the water and scrapped the bottom clean, went to test it again after that and now it seems I got carb problems again, could smell gas when I started it and it ran rouph trying to get up to speed but would never make it, if you tried to keep giving it throttle it would die out. Guess I am going to check the carb again. I really dont know why the carb seems fine one minute and next time I test it I have problem???????????

Jessie"
 
If it's a Holly that is wh

If it's a Holly that is why it is fine one day and won't run the next day. If you had water in the fuel replace all the plugs and ohm test the plug wires if you do not know the last time they were changed.
 
Plugs was changes last year.

Plugs was changes last year. Carb is a rochester 2bbl.
 
"Tested first thing this morni

"Tested first thing this morning. Running about 27mph now so I think most of the problem was a few barnacles that built up on the bottom, did not seem like much but I guess it only takes a little bit to slow you down. Carb ran fine today. Dont know why it seems like it acted up before? All is well for now."
 
replace ignition coil i had o

replace ignition coil i had one that partially broke down and the engine would drop 1000 rpm
stock ford coil has worked in min for 15 years

also fuel filter canister bracket can corrode internally and restrict fuel flow to carburator

check accelorator pump and tower should get 2 large streams of fuel when you push throttle forward min tower got plugged and it was just a matter of putting a wire thru them to open them up only requires removal of one screw to accomplish
 
I took my 302 Ford Mercruiser

I took my 302 Ford Mercruiser 888 and took off the rodchester 2bbl replaced with a Edelbroke hirise performer maniflow and 650 CFM 4bbl carb I went from a 4 blade 14 x18 to a 21 pitch because she pulled much harder.. runs great now also added ACCEL marine distributor and Accel 45000 volt coil this was a rebuilt engine but had the old carb and maniflow and points on it now it runs like the Boss 302
 
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