You replied to a post that is at least 4 years old about my OMC Cobra 5.7 problem.
Searching the archives is great, but it's always best to start a new/fresh thread for a given issue.
If need be, post a link to the thread that you found while searching!
Took it out, won't go more than a few thousand feet and then nothing, "dead in the water."
I'm going to guess I thought I "fixed it" and took it to the lake 20 times trying to figure it out.
Try using the P of E.... process of elimination.... check/replace one item, and one item ONLY at a time.
If you toss a bunch of parts at an issue, and if you are lucky enough to have solved it, you'll never know which item fixed it!
During my time of exploration, I ended up overheating it three times, and rebuilt the out-drive all before getting it to work.
In order - how I came to my conclusion:
change the water separator
FYI..... the only true water separating fuel filter will be the Parker/RACOR.
cleaned the pick-up screen
cleaned the carb filter
cleaned the fuel tank
Good on all of those.
rebuilt the carb
new plugs and points
Are you adjusting the contact points by setting the dwell angle????
Setting point gap is an estimate ONLY of correct dwell angle!
replaced the fuel line
cleaned the fuel tank again
installed an electric fuel pump
FYI.... in order to be legal, the electric fuel pump circuit must include a N/O Low Oil Pressure switch.
new carb
new interrupter switch
There is also an "over-ride" switch. Both the Interrupt and over-ride switches must be adjusted properly.
The ESA adjustment must be made while the boat is in the water.
new mechanical fuel pump
new fuel cell
Please explain! External fuel tank????
Here's where is started getting interesting...
put the electric fuel pump back on
boat runs all day
What did you deduce from that?
Go home and think I have this licked.
Remove the fuel cell
still using the electric fuel pump
take it out and it dies!
What did you deduce from that?
Connect the mechanical fuel pump
fuel cell again
Boat runs great!
Connect to the tank again
Dies!
Again, what have you deduced from that?
Put the old carb back on and remove all the new and put back as was.
take a rubber fuel hose and connect to external tank
Boat runs.
connect to fuel tank
dies.
At the risk of redundancy..... what did you deduce from that?
(keep in mind that I'm posting as though the problem still exists.)
Connect to fuel cell
RUNS!
put it back as it was and take it out...
Wife drives while I play with the fuel pick up
boat dies.
Same as above????
I removed the bottom screen and it would go, just not very long.
What are you calling a bottom screen? The pick up tube screen?
And I'd have to let it rest in between starts as it would stall quicker if I rushed it...
(It was very much like vapor lock)
Have you considered the possibility of mild ignition induced detonation?
The Marine version SBC is almost always fitted with the GM Full Dished pistons, of which makes this engine very prone to detonation if the progressive and total ignition advance are excessive.
Carefully watch your ignition advance on any gasoline marine engine.
It is critical that it be correct throughout the RPM range.... especially at the TA RPM!
Installed a inline fuel pressure gauge.
tested the pick up again
You could watch the pressure drop to zero and a few seconds later dead at any speed.
As you know, the fuel pressure should not drop excessively. The pump should be able to keep up with the demand!
I took it home and cut off the screen end to the pick up.
Took it back to the lake and she ran all afternoon!
The pick up looked as though someone had lengthened it with a splice in the middle.
It was 3/8" copper to 1/2" copper to 3/8" and the screen end.
I cut the whole pick up off from the 3/8" at the top down.
Soldered a new 1/2" copper pick-up onto it.
Took it out and it died.
Dang... not good!
Come to find out the new extension was too long and sucked the bottom of the tank
Notched both side at the bottom and still was stalling
Cut 1/2" off the bottom of the pick-up and been boating carefree ever since.
Excellent!
It would appear the screen end was only 1/4" and too small to deliver the fuel fast enough.
Once I removed it, life was good!
So, there was never actually anything wrong with the boat, motor, or out-drive, and I'm pretty sure the guy I bought it from knew there was some kind of problem as I found boat repair receipts stashed in the cabin storage with a manual. should have been my first clue.
I'm not suggesting this is everyone OMC's problem. This is an old boat [1989] and it would appear it's been worked on several time.
The part that was soooo frustrating was that it ran perfect in the driveway every time, I could throttle it up for an hour.
Testing an engine with no load on it offers very little (if any), useful information.
Only under a load in the water would it starve for fuel through the under sized pick-up screen.
I learned a lot about this boat working on it those years, but even the break downs were fun. The wife would bring food and we'd play cards, and swim and make a day of it every time. I only asked for help once to be towed on a really windy day.
Every time it would stop running I would lash a rope and swim and pull the boat in myself, no mater how far out. Why? To tire the frustration.
We have a great time now, the 5.7L OMC Cobra planes quickly, and moves the 26 foot cuddy to 38 mph with a 15.5x15 prop.
I doubt you would have the same problem, but who knows! Just keep at it and eventually you will narrow it down and fix it.
Again, try using the P of E..... when used systematically and methodically, it will not let you down!
The worst part was the whole thing probably cost me about $500. I have a spare parts now, fuel stuff, a fuel cell, a new carb (spare), and more hours than I can count.
No forum was helpful, all the know-it-alls all gave me the same simple and obvious rhetoric that was never helpful, but I was hoping.
Please don't be disrespectful to the forum members.
And please understand that it is very difficult to diagnose a problem from a key-board.
We have quite a few members here who are very savvy and helpful, but without actually being there with "hands-on" it is very difficult.
Add to it that most people who join the forum for help/answers, are not mechanics, and often do not speak the language, let alone give the best and most accurate info from the get-go!
I also never gave into taking it to the boat mechanic, I saw what they were charging the other guy and it was never fixed. One of the receipts was for $600.
Tip:
Always be willing to pay for proper diagnostics up front.
Authorize the repair ONLY after proper diagnostics have been accessed in written form, and ONLY upon a written work scope "Quote" (not an estimate) that references the diagnostics in the work scope "quote".
Otherwise, you may as well hand over a signed blank check!
One of the first things was how funked-up the fuel tank was, it took two times to get the 60 gallon fuel tank all the way clean.
Drain the fuel from it, use detergent, power washer, and rinse it with water and a shop vac with a 1/2" copper pipe taped to the hose to suck it dry.
While rather expensive and perhaps not easy to find, the non-ethylene gasoline will not give us the same problems that we see occurring with the E-10 or E-15 gasoline.
My family and I are into snowmobiling. Our machines are stored during the warmer weather. Warm weather accelerates E-10 or E-15 gasoline problems! If we were to use E-10 or E-15 gasoline, we could find ourselves having big problems.
I run non-E in all of my toys, lawn mover, garden equipment, etc.
I tried to keep it short. LOL
Hey.... it was a good story, and I fully understand the length of it.
I'm glad that all is good now!