Engine issues

[mowens]

So I rebuilt carb, redid intake manifold, and engine started ran great.

Went to take family out next day and no start just turns over. Fiddled a bit and figured it was a bad coil. Replaced coil and ballast resistor. Now it starts but only as long as your holding the switch in start - which I understood was a sign of bad ballast resistor, which is brand new.

Any ideas?

[prowlersfish]

Yes ,sounds like the resistor , but I have seen the switch do it too . You did not say what model but if you have dual helms try the other one .

[mowens]

454 crusaders with quadrajets.

It was a bad resistor. Put another new one in fired right up.

Now the new problem is the fast idle set about 2500 RPMs. I don't see any kind of adjusting screw.

[prowlersfish]

454 crusaders with quadrajets.

It was a bad resistor. Put another new one in fired right up.

Now the new problem is the fast idle set about 2500 RPMs. I don't see any kind of adjusting screw.

Fast idle screw is on the same side as the choke linkage (well hidden )

[mowens]

So on mine it looks like the front piece once held a screw but it doesnt now. Whats funny is the other carb is the same but fat idles perfect at 10k

Hope this shows what im seeing. That large flathead screw doesnt seem to do anything except hold those parts on.

[prowlersfish]

Forgive the poor photos of photos . The screws viewed from the bottom of carb . I have always hated chokes on a boat , I used to set my lean or open by disconnecting .But you have to play with the throttles till they warm up a bit Nice thing about diesels no choke . Did I tell how much I hate chokes on a boat ?

I am not 100% all did have the screw ,but thinking they did and always had trouble seeing it . And that was in the old days when I had good eyes .

[mowens]

I see what your referencing. Mine does not have that screw. It does have threads for one though.

Yea chokes suck lol I do like diesels but in not spending that yet.

So since my screw does not exsist is tgere a different way? The other motor also does not uave the screw but fast idles perfect.

[mowens]

Tried a few things still can't get the fast idle down.

Ran the boat yesterday for 22 miles top speed 21.4 mph. When we started out had a sound kind of like a pressure release ping of metal. Ran stbd at 3k rpm port 2.5k rpm as we came in port sped up to 2.7k on it's own. As we slowed down in the marinas no wake zone heard the port sound like a small backfire through the carb like a puff.
Stbd / port
Temps ran. 170 / 185
Oil pressure 40psi / 30psi

Not sure what else to do here. I'm tunning the carbs this week. Going to do a flush on the cooling system
Oil change with marvel mystery oil


Po claimed new impellers both engines and new plugs port side.

[captainmaniac]

Couple of things... both temps - way too high. Running engines at different RPMs - why? If they were actually in synch you have gauge or wiring issues, if they were not in synch and you just chose to run them at different RPMs..... just gonna leave that one alone for now. 21mph for WOT - you are down at least 7-10 mph of what it should be doing. Bottom line, think you have lots of issues.

[prowlersfish]

Was that running wide open ? When was the bottom last cleaned ? Fresh (closed) or raw water cooled ? What weight oil ? Why the snake oil ?(marvel mystery oil) it thins the oil .

And have you checked the firing order ?

On the high idle engine make sure all the choke linkage is free and check to make sure the secondary's are not partly stuck open . also make sure the high idle cam is on right .

[mowens]

Couple of things... both temps - way too high. Running engines at different RPMs - why? If they were actually in synch you have gauge or wiring issues, if they were not in synch and you just chose to run them at different RPMs..... just gonna leave that one alone for now. 21mph for WOT - you are down at least 7-10 mph of what it should be doing. Bottom line, think you have lots of issues.

The temps being high yes why i plan a flush and clean out the passages.

Different rpms that was wot I should have clarified that point. The synch gauge sits dead center never moves I think its toast. I ran then at 2.5k rpm generally.

I'm sure I have lots of issues why I'm asking trying to figure it out. Lol

Was that running wide open ? When was the bottom last cleaned ? Fresh (closed) or raw water cooled ? What weight oil ? Why the snake oil ?(marvel mystery oil) it thins the oil .

And have you checked the firing order ?

On the high idle engine make sure all the choke linkage is free and check to make sure the secondary's are not partly stuck open . also make sure the high idle cam is on right .

Yes that was wot. Bottom cleaned a month ago. Fresh water. Currently 30w. the mmo does thin out also has some solvents that break gunk down helps loosen rings etc. I was going to add it run the engine for a bit then drain and go fresh with rotella 15w-30

Checked firing order

I think its something wrong with the fast idle cam they look the same both engines as far as I can tell.

[prowlersfish]

You may have posted this , all fuel filters clean ? including the small ones in the carbs ? If the chokes are not 100% open the secondary's will not open

Oil 15w-30 ?? You mean 15W-40 ? That or straight 30 or 40 ( warm/ hot areas) no snake oils please

[mowens]

Yea, just rebuilt carbs and filters and the antisyphon valves.

I thought 15w30 I'll go 15w40 and its hot here South Alabama.
I haven't watched secondaries but have seen the choke go fully open.

[mowens]

Continuing saga.

So took the boat out friday ran 14miles out fished a bit and drove back ZERO issues. Ran avg 21mph at 3k rpm I could have pushed more topped speed at 26mph close to 3500 rpm.

Today I took the boat out again. I took the boat out again and went 17miles out no problems.

Turned home went aobut 6 miles STBD motor started dropping rpm wouldnt get over 2k and would try to die if I held the rpms up. If I let it go down to 10-15 it worked but surged. As we got closer to shore It stopped doing that and ran up to higher rpm but started to click or knock and I really hope it isnt what I think it is. Lot of steam out the exhaust. Check oil when got to dock and looked fine not lower that I could tell and black (needs a change yes) but not fouled anyway I could tell. I am at a loss as this motor has been pretty spot on since I got the boat. Put my hand on the exhaust elbow it was hot but not more then usual.

PORT motor ran fine until we got the last little bit home then it wanted to act stupid as well and wouldn't throttle up either sounded like it was sucking air or trying to run out of gas over 1500 rpm.

I tuned carbs prior to fridays trip via vacuum at 19 psi and it ran great
added 60 gallons of fuel split between tanks for this trip
temps never went past 170 at 3k rpm and stayed closer to 150 at low rpms
STBD oil pressure was 30-40psi POrt was 40-50 been like that since I got it not sure why the difference.

If anyone has any Ideas im alll ears. I am trying to find a mechanic to come look but nobody seems to do that anymore.


TIA

[rossjo]

I do like diesels but in not spending that yet.

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• Video running 27knots in Charleston Harbor, SC: https://youtu.be/8qfSZ4Rmbeo

• Video of transom, cockpit and bridge while idling at dock: https://www.youtube.com/watch?v=w3xRVYu5Epw

• Video of Cummins diesels startup and running: https://youtu.be/zKMhBzFhxu8

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