460 engine dies

[jvnd]

I have a 1978 460 ford motor jetboat that dies after a short time. It will start up fine and I can take the 5 year old granddaughter for a run so she can see my "turkey tail" run and then the engine will act like it runs out of fuel. I can immediately start up again. I had a friend check the carb while we ran and he said there was fuel the whole time. I idled in the water and took the motor up to 3000 rpm and it ran fine until that point. I did this over and over and the same result. As long as I don't go past 3000rpm I'm fine. Doesn't do it in the driveway. Also the vacuum secondarys stick. I have rebuilt the carburetor and checked linkage. It doesn't do it with the motor off. When I manually work the actuator rod it doesn't want to go back down completely, I have to pull it down. Finally, my amp guage is showing a negative charge. I checked wiring and found a disconnected wire (field?). Connected it back and no change. Used a handheld little alternator checker with a probe and alligator clip to ground and it showed ok. Any help is greatly appreciated.

[jvnd]

Floats adjusted and accelerator pump diaphraim brand new.

[LakesOnly]

These symptoms could point to a number of things.
If you are running a points distributor, I suggest you change out your points and condensor. I'll bet that either the rubbing block has worn down on the points and the gap has closed between the contacts just enough to cause your symptoms, or your condensor is failing. The condensor failure is an often overlooked/hard to find failure but your symptoms match it perfectly.
The lack of charge may not be related; check grounds.
In regards to your symptoms and the relevance to fuel delivery: check for water in the gas...in the fuel tanks and the float bowls.
That ought to be a good start in your diagnosis....
LO

[roostwear]

Some vac sec carbs have a "check ball" in the vacuum housing base to prevent sticking. Pull the top off and look to see if there is one in the vacuum port.
You might hook up a fuel pressure gauge and check how much pressure/drop there is from your pump before and after your 3k threshhold.

[jvnd]

Lakesonly I will do what you say. It is an Accel dual point distributor and I haven't replaced the points or condenser. I looked at the points but that was it. There is no water that I can see and I do have a water separator. Rootswear, I have the checkball in place. Anyother ideas? Thanks to all for your help.

[SmokinLowriderSS]

I have had a bad coil that behaved the same way, till it got worse, and the RPM break-up point went down.
Would run great, till it got hot, then would refuse to run above a certain RPM, untill shut off long enough to cool significantly, then was fine, untill heated again.

[jvnd]

I have a new coil I'm also going to use. I had a helper check the coil for heat and it wasn't hot. But it can't be that because the boat will start up immediately. As long as I don't go above 3000rpm I can run all day. It doesn't do it in the driveway. Just under load.

[SmokinLowriderSS]

I have a new coil I'm also going to use. I had a helper check the coil for heat and it wasn't hot. But it can't be that because the boat will start up immediately. As long as I don't go above 3000rpm I can run all day. It doesn't do it in the driveway. Just under load.
That is EXACTLY how my coil acted, for the first 2 days.
I cannot tell you how "hot" the coil was, because I never grabbed it, but the internal heat or whatever was causing it to break down and miss-fire like it hit a rev-limiter.

[Moneypitt]

Use a jumper from + battery to + coil, just as a test......Fixed? go back towards the switch, as in switch side of the ballast resistor, still OK...Kepp chasing it back towards the switch until it fails.....OR hot wire = no difference, now you know it is down stream from the 12v to the coil and can work from there towards the spark plugs.................MP

[HemiDude]

" Friends don't let friends drive Fords " :D :D

[XJBones]

I have a 1978 460 ford motor jetboat that dies after a short time. It will start up fine and I can take the 5 year old granddaughter for a run so she can see my "turkey tail" run and then the engine will act like it runs out of fuel. I can immediately start up again. I had a friend check the carb while we ran and he said there was fuel the whole time. I idled in the water and took the motor up to 3000 rpm and it ran fine until that point. I did this over and over and the same result. As long as I don't go past 3000rpm I'm fine. Doesn't do it in the driveway.
I had a similar problem with my 460. It ended up being a plugged filter screen in the tank pick up. Started fine but fuel pressure would drop of at about 4K rpm and it would occasionally die while going at a constant 3-3.5K. Without a loaded pump you won't be sucking as much fuel setting in the drive, so I would expect it to spin higher without a problem.
Good Luck,
Bones

[jvnd]

If it was a plugged fuel line wouldn't do it all the time? My problem isn't evident until about 5 minutes after I start it and go on a full speed run. I'm in the process of changing the points and condenser. Also I have a new coil laying around so I'll throw that on too. Maybe. If not I'm wondering if a fuel line is starting to collapse if it gets warm?

[firstjetinMN]

I have a 1978 460 Ford and it does the exact same thing as yours:
The motor :
Full Roller
10.5 to 1 compression
Edelbrock RMP intake
750 cfm Demon
Things I have tried:
Flushed the tanks and put in new gas
New fuel lines (no collapsing here) nor water in the fuel
Installed a fuel pressure gauge, has constant 7.5 psi at all times
Demon carb was rebuilt at the beginning of the season and is perfect
Checked all wires from distributer, ballast resister, etc, etc, all OK
Checked the Unilite in my mallory distributer and it tested exactly to spec
New plugs and wires, rotor and cap
Checked for air leaks around carb base
Checked over all of the ignition wires
2 full tanks of fuel, no issue with one tank empty
Made sure gas caps were vented
I can idle around and it runs like a champ, stay into the gas for a while and it bogs out and stalls...... AFTER warming up, sometimes runs for 5 minutes, sometimes runs for 10 minutes. Starts right up after shutting down, except when really warm. Once it cools down it runs like a champ again for 10 minutes. Doesn't seem to be a specific RPM, but usually over 3 grand. Engine runs 130 degrees all day long. Running through transom rewarder headers.
Last two things I am going to try before throwing a fit:
Replace my Mallory coil
Upgrade my distributer to an MSD and junk this piece of crap Unilite
Good luck and let me know what you end up finding in the end....curiousity has the best of me

[Jim Hall]

I,ll join this club:sqeyes: I have similiar problems and am down to the last three items,distributor (old points Mallory converted to Pertronix),Alternator not producing enough at higher rpm and maybe coil which I changed out last year with no change.Mine runs like a scalded ape to about 4900-5000 and then goes flat at that time it is only about 5/8 throttle.
I have changed carburator from reworked 750 to the present 1050 dominator and am running fuel pressure @9psi,no change.I am checking alternator tonight and if I checks out I will breakdown for new MSD ditributor. I feel your pain!
521 ci
ported pi heads
10-8-1 comp
1050 dominator on dual plane weiand stealth
cam 108cl 583in 600ex 240dur

[XJBones]

If it was a plugged fuel line wouldn't do it all the time? My problem isn't evident until about 5 minutes after I start it and go on a full speed run.
If the line was completely plugged it would be a constant no fuel situation, but if it was only partially plugged (restricted) it would take a bit of time to drain the fuel bowls as demand outpaced supply obtainable through the restriction.
Bones

[firstjetinMN]

If the line was completely plugged it would be a constant no fuel situation, but if it was only partially plugged (restricted) it would take a bit of time to drain the fuel bowls as demand outpaced supply obtainable through the restriction.
Bones
Would you not lose fuel pressure if you had an obstruction in the line or tank pick up? If the gauge shows a constant pressure it should have a good even flow of fuel

[jvnd]

I had a buddy check the carburetor as I drove and as it began to lose power and he said there was plenty of fuel and even manually pushed up on the secondary diaphraigm(sic) and said it had fuel. Thanks for all your input and first one to solve their problem and pass it on gets bragging rights. BTW I'm planning on putting in a point replacement for the Accel dual point. Do they make it for a dual point and does anyone know the number off hand? I'll also try the Accel website.

[XJBones]

Would you not lose fuel pressure if you had an obstruction in the line or tank pick up? If the gauge shows a constant pressure it should have a good even flow of fuel
Yes, but it would vary by needed fuel flow. I had good fuel pressure at idle and just off idle. The pressure didn't start to drop off until about 3K RPM by 4K it would drop to 1 or less and lean out the engine as the bowls dried up.
I had a buddy check the carburetor as I drove and as it began to lose power and he said there was plenty of fuel and even manually pushed up on the secondary diaphragm(sic) and said it had fuel.
Mine still had some fuel passing at 4.5K but not as much as it should and it was leaning and running like sh*t.
IIRC you said the problem wasn't noted out of the water.
Doesn't do it in the driveway...
With no load on the pump you aren't using near the fuel you would on the water because the pump is not pushing a load, so fuel starvation wouldn't show up nearly as easily.
Check your fuel pressure as you run the boat in the water. If it stays constant at 5+ you’re probably not dealing with a fuel line obstruction, but if the pressure drops you need to check the feed to the pump and the pump/filter system.
Bones

[DMOORE]

Check your fuel pressure as you run the boat in the water. If it stays constant at 5+ you’re probably not dealing with a fuel line obstruction, but if the pressure drops you need to check the feed to the pump and the pump/filter system.
Bones
Also make sure the tank vent is working properly.
Darrell.

[Jim Hall]

Check your voltage to coil.I found a big voltage drop to mine.Had a bad wire and connectrion.If the coil is not putting out enough it will cause the same symptons.I won't know till this weekend what the results are.

[DUCKY]

If you have any type of a self venting fuel fill, pop one (the tank you are using...:D )
open next time it happens and see if there is an improvement.
I am surprised no one mentioned those stupid "anti-siphon" valves comonly found on the tank outlets. A slightly sacked out fuel pump will not open many of those up. I would consider losing them, as they tend to be a constant source of problem of a performance boat.
Also, take a good look at your fuel lines before the fuel pump. I have seen some of the smallest cracks in rubber hoses cause problems like this. It doesn't take much of an air leak on the suction side of your pump to ruin your day, or your motor.
On the sticking secondary thing, I am going to ask a really stupid question.... There is a spring in there, right? I have seen many a "Holley Carb Guru" try to remove no only the check ball, but the spring as well.

[Moneypitt]

I,ll join this club:sqeyes: I have similiar problems and am down to the last three items,distributor (old points Mallory converted to Pertronix),Alternator not producing enough at higher rpm and maybe coil which I changed out last year with no change.Mine runs like a scalded ape to about 4900-5000 and then goes flat at that time it is only about 5/8 throttle.
I have changed carburator from reworked 750 to the present 1050 dominator and am running fuel pressure @9psi,no change.I am checking alternator tonight and if I checks out I will breakdown for new MSD ditributor. I feel your pain!
521 ci
ported pi heads
10-8-1 comp
1050 dominator on dual plane weiand stealth
cam 108cl 583in 600ex 240dur
This one sounds like valve springs.......But it also seems like an awful lot of fuel/camshaft for less than 11 to 1 compression.........MP

[DansBlown73Nordic]

I had a FORD once. It was a 460. I spent more time under the hood then in it. It use to break the roll pin for the oil pump drive......I fixed that problem FAST!!!!! SOLD!!!!!!!!!!!:D

[Jim Hall]

I ran mine today and it finally worked after 4900 rpm.Curing the the voltage drop and eliminating the ballast resistor did the trick for me.Make sure your coil has the correct volts going to it.

[firstjetinMN]

I ran mine today and it finally worked after 4900 rpm.Curing the the voltage drop and eliminating the ballast resistor did the trick for me.Make sure your coil has the correct volts going to it.
You said you had a petronix? I am unsure if that is similar to my Unilite...but I was told if I were to run it without the balast resistor it would fry the module out ? :eek:

[DUCKY]

You heard correctly. Don't try to run a Unilite without some form of voltage protection. They are designed for use with 12v, but they are very sensitive to spikes. one blast to 15v (which alternators do all the time) and it's toast. If you don't run an alt, you can probably get by without the ballast.
A Mallory Unilite is a Hall-Effect trigger, which uses a photo sensor, and that photo sensor is what burns out. A Pertronix is Magnetic pickup. They are completely different.

[SmokinLowriderSS]

I,ll join this club:sqeyes: I have similiar problems and am down to the last three items,distributor (old points Mallory converted to Pertronix),Alternator not producing enough at higher rpm and maybe coil which I changed out last year with no change.Mine runs like a scalded ape to about 4900-5000 and then goes flat at that time it is only about 5/8 throttle.
I have changed carburator from reworked 750 to the present 1050 dominator and am running fuel pressure @9psi,no change.I am checking alternator tonight and if I checks out I will breakdown for new MSD ditributor. I feel your pain!
521 ci
ported pi heads
10-8-1 comp
1050 dominator on dual plane weiand stealth
cam 108cl 583in 600ex 240dur
Exactly what is this in?
I've seen people have this exact same complaint, in a jet boat, and there was nothing wrong. That is to say, they reached the RPM level at 3/4 throttle (or so) that the pump absorbed the maximum available engine power, and the last 1/4 of throttle did absolutely nothing, because the engine was maxed out against the pump already.

[Jim Hall]

It's in an 18' Avenger with an Aggressor B impellor.I tried it this past weekend with the full 12v to coil and it made a big difference.I still need to do some tuning but everytime I go out it get's a little better.I thought about running out of power with the impellor but it keeps picking up.I just built this engine over the winter so I'm still working the bugs out.The valve springs are the only unknown and will probably get them matched up with the cam this winter.

[centerhill condor]

Also, take a good look at your fuel lines before the fuel pump. I have seen some of the smallest cracks in rubber hoses cause problems like this. It doesn't take much of an air leak on the suction side of your pump to ruin your day, or your motor.
I agree with the fuel line thing. If you have a bend check for closing off, do away with kinks. Also, if you have spin on fuel filters check your gaskets...sometimes they deform/slip and allow air to infiltrate the fuel system. That would give pressure but not fuel!
Best of luck..you've gotten some good help here. These guys are the best!
CC

[jvnd]

Thanks to all who are trying to help. I'll try to respond to each issue. I tried a different fuel pump while on the water and no change. I do have anti-syphon valves but years ago when I tried to run without them I couldn't so I can't get rid of them. I have pop-up fuel fillers with a spring loaded seal. I have no vents. Boat ran since 1978 without very well. The vacuum advance spring and ball are in place. Even tried a different vacuum unit and no change. I'm putting in a different coil and changing the points (Accel dual point) and condenser. I don't know when I'll get to try it on the water though since I'm starting a new career (after owning a construction business for 23 years) as a OTR truck driver. I currently have the boat for sale because I very seldom use it anymore (1 yearly trip to the river) so I want to make sure I don't pass along any problems. This boat has performed flawlessly for me for almost 30 years. Sad day indeed.

[Scapegoat1]

I had the same issues I would open the gas cap and close and boom started
vent the tanks

[jvnd]

Well it's run great since 1978 without changing the fuel setup except for the original design was Southwind had it pull off both tanks together and I'd run out of gas in one tank while the other was full so I put in a fuel selector and separate sending units. I really don't think its a fuel problem because a buddy watched the carb as all this happened and said fuel was present. I also found my charging problem. Bad connection at the alternator of the main wire (10ga). When I was checking the wiring it just fell off. So one down, two to go.