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ksr8s
06-27-2007, 01:00 AM
I have an '87 ProStar 190 with the Ford 351. Last year it was running very poorly so I decided to do a little work on it and replaced the spark plugs and wires as well as rebuilt the carburetor.

That fixed all my problems except one. The boat seems to randomly make a loud "popping" noise. The noise occurs at any RPM above 2000 and doesn't seem to depend on the engine being under load. The popping repeats quickly and, fearful of engine damage, I have not tested to see if it will go away without bringing the engine back to an idle. The volume of the noise seems to depend on RPM. It has ranged from a soft pop at 2400 RPM to a loud noise heard from the other side of the lake at the high end.

I appreciate any help on troubleshooting this problem. What ever the noise is, it sure does scare people. :)

P-hat_in_Cincy
06-27-2007, 07:55 AM
A 'pop' as in a backfire?

scott88prostar
06-27-2007, 07:58 AM
I think your spark plug wires may be crossed.....the firing order is stamped on top of your engine ....in front of your carb.

read this post.

http://www.tmcowners.com/teamtalk/showthread.php?t=1010&highlight=firing+order

ksr8s
06-27-2007, 03:44 PM
I'm not sure if it is a backfire or not. I've never heard a boat backfire. It doesn't sound quite right for a backfire

I've checked the spark plug wires, they are in rough shape but correct. I plan to replace them in case there is some interference causing a cross fire.

All of that then lead me to check the distributor cap for arcing. It didn't show any evidence of that. However the points haven't been replaced in at least 5 years.

I'm thinking that with new wires, distributor cap, rotor, and points my problem might be fixed.

TMCNo1
06-27-2007, 03:56 PM
I'm not sure if it is a backfire or not. I've never heard a boat backfire. It doesn't sound quite right for a backfire

I've checked the spark plug wires, they are in rough shape but correct. I plan to replace them in case there is some interference causing a cross fire.
All of that then lead me to check the distributor cap for arcing. It didn't show any evidence of that. However the points haven't been replaced in at least 5 years.

I'm thinking that with new wires, distributor cap, rotor, and points my problem might be fixed.

I read in post #1 your replaced the spark plug wires.
I would go ahead and contact www.skidim.com and get a Electronic Ignition Conversion Kit, 12v coil, replacing the points and condenser, a new rotor button, distributor cap, spark plug wires and be done with the points setup.

TWalbrun
06-27-2007, 04:03 PM
I had a similar issue with my 1985 Prostar 190. It was ultimately the carb and tach. I had the rebuilt, but the issue remained. I thought the mechanic was crazy when he said that the tach was bad and it was causing the back firing through the carb -- making the carb bad. Just a side note, the needle on the tach had been bouncing. The mechanic replaced the tach and I have been problem free.
Another side note, this guy is not only a friend, but was the head mechanic at a major MC dealer for a number of years.

ksr8s
06-28-2007, 09:44 PM
The Electronic Ignition Conversion would be nice if it were less expensive. Thats out of my range right now.

JimN
06-28-2007, 10:19 PM
ksr8s- if the plug wires are in rough shape, that's the first place to look for problems. Get rid of them and eliminate that as a source of the problem. Also, I don't know what your experiences are but if you're more familiar with GM motors, Ford doesn't number the cylinders the same way. 1-4 are on the left bank, looking from behind.

WTRSK1R
06-28-2007, 10:58 PM
Sounds like point float to me. I had a car that did that intermittantly until one day it backfired so bad it completely blew out the seam on the muffler. Ultimately, after replacing the muffler, I put a new set of points in, and all was well. I think the spring was weak and they were bouncing. But as stated by several people, replace the plug wires.

JEREMY79
06-29-2007, 07:13 AM
The Electronic Ignition Conversion would be nice if it were less expensive. Thats out of my range right now.

Go to any auto parts store and get distributor, coil and an igniton module, then find you a mechanic that works on fords. Tell him that you would like the wiring from the ignition module to the distributor and coil, or even do it your self(you just wont have the plugs) BAM electronic conversion

mpm32
06-29-2007, 11:22 AM
I wouldn't use an auto distributor in a boat. Marine dists are sealed to prevent sparks from escaping. Guess what happens when you get a spark in a gas vapor filled engine compartment?

wesgardner
06-29-2007, 12:29 PM
http://www.performancedistributors.com/marinedui.htm

This is undoubtedly the way to go...

ksr8s
06-29-2007, 05:09 PM
I wouldn't use an auto distributor in a boat. Marine dists are sealed to prevent sparks from escaping. Guess what happens when you get a spark in a gas vapor filled engine compartment?
Not to mention the issues with moisture getting into the distributor.

Sounds like point float to me....
I really hope your correct. I've been also getting advice from a guy who spends weekends as crew chief on a Ford racing team. He said basically what your saying.

ksr8s- if the plug wires are in rough shape, that's the first place to look for problems. Get rid of them and eliminate that as a source of the problem. Also, I don't know what your experiences are but if you're more familiar with GM motors, Ford doesn't number the cylinders the same way. 1-4 are on the left bank, looking from behind.
I have checked the firing order with the original owner's manual, the re-released manual on Mastercraft's site, and the current wiring order. They all checked out the same. I'll be replacing the wires in those orders. I noticed that Chevy has a very different numbering system for cylinders and order.

I will be doing this tonight or tomorrow. The rainy stuff finally cleared up. :D

east tx skier
06-29-2007, 05:19 PM
Mine did this the first run of the year. Turns out one of my plug wires had come loose. Reattached it and no more popping. Re-replaced that plug when I got home. Since you'd just replaced yours, check to see if they're all on their good.

JEREMY79
06-29-2007, 09:02 PM
I wouldn't use an auto distributor in a boat. Marine dists are sealed to prevent sparks from escaping. Guess what happens when you get a spark in a gas vapor filled engine compartment?

When I have a problem I will let you know

Lennyp04
07-03-2007, 05:31 PM
We had what i think is the same problem in our old I/O which was a 1986. We didnt really want to get into it so we got the new boat but we thought that it was a timing issue, that the pistions were misfiring