460 idles fine, backfires and dies when trying to plane out

[shmuck2002]

Hi all,
Here's my setup:
Ford 460, Bassett short tube water injected, berkeley jet. Holley red fuel pump w/ regulator set at 4.5 psi.
Quick history on the problem:
Boat ran great for a full season, then I had a mishap with a bad fuel cap seal and got water in one of the tanks. Discovered the water issue while out on the water ;) Drained and flushed both tanks and the whole fuel system, fixed the bad fuel cap seal, and we were good to go for a long weekend at the lake, ran about 5+ hours without a hitch. Next time out, ran well for about 45 minutes, then started having a problem with it running strong for about 90 seconds, then would stall. Would not start up again for about 3 minutes, then would repeat the same pattern (as we're desperately trying to get back to the launch from the furthest point on the lake!!).
I had thought I ended up with water in the fuel again, so I pulled the fuel line off the carb and ran it into a clear container, where I would see the water collecting on the bottom, however no water this time. Went ahead and completely flushed out the fuel system again, and out for another test.
This time, it's even worse: idles just fine, no missing, and when i get out past the no wake zone and start to plane it out, it backfires, and dies. Turned around and idled it right back to the dock.
so i guess my question is... HELP!!! :)

[nova1]

Just an thought. I had a 460 in a jet boat for 10 years. Start boat out side water with hose or back trailer into lake (best) . Start and idle. I always had my regulator set at 6.5 psi for a 4bbll carb. Check your carb spec by calling Holley.
You should be able to have someone run motor up and you view the fuel sight glass to make sure fuel is at the right levels. And watck your fuel pressure, it should stay the same.
This may show you a little whats happening, You may be running low on fuel when you step on the gas.
Also, slim chance, you may still have some water laying in the bowls.
I know technology is king but I still like the mech. fuel pumps.
I have seen many strange things happen to MSD boxes and ign. systems when your voltage drops below 9v-10v for some reason.

[HOSS]

4.5 is too low, I`d be like said at 7. I too think your running out of fuel in boals. As said, check site glass. Another thought. Sure you dont have bent valves or broken exhaust valve spring(s)?

[shmuck2002]

Hey guys, thanks for the replies! I am running an Edelbrock 1409 (600cfm) carb, and I have the original manual for it, so I will verify recommended fuel pressure, and the float window. Also will drain the bowls to check for water. Sounds like a run to the "test lake" for me this weekend!! :) Will post results soon

[justfloatn]

There is still water in the carb somewhere. Draining the bowls will still leave a drop or two in there in a passage or corner of the bowl and that is all it takes. You will need to dissassemble the carb and spray it out with brake cleaner.:)

[shmuck2002]

Thanks JustFloatin, I am suspecting water as well, since that was the root cause of my initial problems.
PS, love that avatar!!

[Wet Dream]

Take the carb off, remove top, turn upside down and squirt every hole with cleaner until it comes out somewhere else. Remove jets too.

[shmuck2002]

Hey guys,
I finally got time to work on the boat this weekend. I pulled the carb, pulled it apart and drained the bowls (no water, clean fuel), and blew out all ports. The only place I found any gunk was the pump jet sprayers. Cleaned them out carefully and made sure they were both spraying smoothly.
Hooked the boat up to the garden hose, she runs fine, and up about 4000 rpm, she starts doing small backfires. Holding the throttle in that range, it doesn't stall and RPM doesn't fall, but the mini backfires remain constant. letting off the throttle hard or soft, it does not stall, idles quite well.
What do you suggest at this point?

[H20MOFO]

I hated my edlebrock carb. Every spring it would start and run but just sickly. It may or may not be your issue, but like wet dream said take it apart and spray every hole out. I know you already did that, I had to use a compressor and some serious psi. Wear glasses, the last chunk of crap I blasted out of there missed my eye by a centimeter. I'm certain carb cleaner wouldn't have touched it. If you know someone you can borrow another carb from that would be a bonus.....maybe you just need a tune up....but what you describing sounds exactly like my 1st trip out every spring.

[shmuck2002]

Thanks H2O, i'll pop the carb and go at it with the compressor (and safety glasses!). Any other suggestions out there from the masses? possible timing issue? plugs?
I pulled each plug yesterday to inspect, most were light brown in color, and a couple were black. From the previous owner and the shop notes, it uses "25" plugs, which I presume is a gapping reference.
Just trying to cover all my bases here. My fear is, although it runs "pretty good" on the hose, I'm going to get it out to the lake to test, and find that under load, it does the exact same thing it did the last time it was in the water. either way, even if it runs the same on the water as it is on the hose, I am not satisfied with the backfiring it is doing.
PS - from reading in other threads, this seemed to be important: it is backfiring thru the exhaust, NOT back thru the carb.

[H20MOFO]

You may want to try a compresion test,and or a leakdown. Poping through the exaust could be a burnt valve. or head gasket. Hopefuly not.

[justfloatn]

You could be chasing the wrong problem. Backfires in the exhaust are useualy a secondary ignition problem. Unless you have raw fuel dumping down the carb when ideling or accelerating. That you would see. If it were somthing plugged it would probably backfire through the intake. When was the last set of cap & rotor, plugs or wires installed?
It sounds like you are loosing more than one cylinder so the cap and rotor are where I would start. Plugs are a must if your carb was the problem. If you have an ohms meter check the wires. If you have one or more with excessive resistance that could be the problem. Or if they are five or more seasons old change them. I would check the timming too.
Back to basics..:D

[DK_Hallet]

Try another Carb . That should eliminate any ? about whether that is your problem. Its always the simple stuff that kills you. Thought of one more thing . What Distributor do yo have. Check the hold down and check the advance also . Trying to give the easy checks first .. hope that helps

[BrotherWolf]

You could be chasing the wrong problem. Backfires in the exhaust are useualy a secondary ignition problem. Unless you have raw fuel dumping down the carb when ideling or accelerating. That you would see. If it were somthing plugged it would probably backfire through the intake. When was the last set of cap & rotor, plugs or wires installed?
It sounds like you are loosing more than one cylinder so the cap and rotor are where I would start. Plugs are a must if your carb was the problem. If you have an ohms meter check the wires. If you have one or more with excessive resistance that could be the problem. Or if they are five or more seasons old change them. I would check the timming too.
Back to basics..:D
this is were Im starting, I had a simular thing happen to me yesterday while at the lake.....after about 5 min at full throttle it sounded like it was starving it self and was making a loud noise, if I let of the pedal it ran fine but every time I got on the gas 5 min was top and it would start running like crap then the last time it did that it started backfiring out of the carb...and now when you try to start it it just pops..ugh...Im hoping its not a sucked valve or the timming chain slip a few teeth:eek:

[Legal Chemistry]

I had the EXACT symptoms, unfortunately it was burned up valves. If you think about it, to me it makes sense with the water in the fuel. A leakdown should tell you if it's the valves. Good luck.

[justfloatn]

this is were Im starting, I had a simular thing happen to me yesterday while at the lake.....after about 5 min at full throttle it sounded like it was starving it self and was making a loud noise, if I let of the pedal it ran fine but every time I got on the gas 5 min was top and it would start running like crap then the last time it did that it started backfiring out of the carb...and now when you try to start it it just pops..ugh...Im hoping its not a sucked valve or the timming chain slip a few teeth:eek:
Do you have a fuel pressure gauge. This sounds more like fuel starvation. Possibly a plugging fuel filter. It allows the fuel flow to keep up at low rpm then slowly falls off under half or full throttle untill the engine leans out and backfires out the intake. I have also seen electric fuel pumps do this when they start to quit. They work good when cold and as they get hot they get weak and fuel pressure drops off. I just hope you didn't run it too lean for too long and burn a valve or piston.

[bp]

after reading all this, it's an ignition issue period. if there were something wrong with valves/valve train, it would not run even close to well up to 4000 rpm, and after all the attention to the fuel system, it's not fuel.
i've had problems similar to the symptoms you describe in the past; it's always electrical or ignition related.
someone suggested cap/rotor, great suggestion. cap/rotor can cause the problem you're describing. but, a better description of your ignition system would be helpful. check every ground connection on the boat, make sure no ground wires are scrunched or hitting anything, make sure all ground connections are clean and tight. check other electrical connections to make sure they are clean and tight.

[SBC Jetboat]

Well, I can tell you that that Holley fuel pump is garbage. They NEVER flow the fuel they are supposed to. N E V E R and Ive got friends who have had the same experiences. Wouldnt you think a pump supposed to flow 69 gph would keep up with a mild small block that is pulling 23 gph on a flow scan fuel flow meter??? Well it wasnt keeping up. I just run the high flow mechanical pumps now. You do need more than 4.5 psi. Should be more like 6 or 7 but you need a fuel pressure gauge on the dash to make sure you are MAINTAINING proper fuel pressure. Good luck

[VAMI]

That 25 your talking about is the heat range number not gap thats way to small should be .035/.040,I think thats a autolite number.If you had burnt valves it would pop at idle too and head gaskets would show milky oil.For sure try another carb to eliminate that then check out your ignition its one of the 2.

[BrotherWolf]

Well i got into my boat today and thought I would start with cap, plugs, and wires. Well to my suprise 5 of the 8 spark plugs had busted electrodes and no gap??????.....my first thought was W.T.F?????......So I threw in some new plugs and hooked up the hose and fired it up and sounded great and no pop.
I was so pumped up and was going to head to the lake to run the boat and thought I better check the oil.....now I got milky freaking oil...UGH!!!!!!..,,,Off to the store for some head gaskets.....what brand do you guys recommend??
for a 460??

[SBC Jetboat]

Felpro

[BrotherWolf]

Felpro
the ones that have the silcone around the ports??...what about the copper ones??

[justfloatn]

Copper is for high compression and works best with an 0-ringed block/heads.
Save your money and get the basic High Performance gaskets

[shmuck2002]

Hi guys,
Getting back to my original post, I would like to start exploring the possibility of an issue in the ignition system. When it comes to engines, this is the part I know the least about. Attached is a picture of my distributor and coil.
I've popped the distributor cap off before to inspect, there's no sign of wear, or burns from arcing. No signs of cracks, and there's no corrosion or contaminants where the plugs come in.
here's the picture: http://cobraftp.serveftp.com:81/pub/ignition.jpg

[shmuck2002]

Hey guys,
My problems seem to be fixed! Last week I replaced the distributor, plug wires, and plugs. After setting the timing to 13 degrees, she was running good, however still getting those mini backfires at high RPM when on the trailer. I decided to go ahead and pull it up to the lake and just give it a try. She runs better than the day I bought her! Very strong, responsive, and no troubles at WOT, for several minutes across the lake. Everything seems to check out now.
What I'm wondering is, was I chasing the wrong problem from the get-go? The mini backfires, is that possibly caused because the motor is spinning under no load? It did not do that, or anything fishy, after a full day of running it. I tested it again after getting it back home, and it still does the mini backfires when running with no load.

[460rogers]

Ford 460, having a problem with it running strong for about 90 seconds, then would stall. Would not start up again for about 3 minutes, then would repeat the same pattern (as we're desperately trying to get back to the launch from the furthest point on the lake!!).
This sounds like a classic coil going bad scenario to me.
Have you changed the coil???
Just my .02

[firstjetinMN]

Had the same issue with my 460 Ford..... Replace the coil, they are cheap. And by god don't ever run a Unilite in your distributor...They are junk and will drive you made, they are unrealiable and break like nothing.

[shmuck2002]

Hey guys,
The distributor unit I installed is an Accel. The only thing in my ignition system that has not been replaced is the coil - Is there a particular one you guys recommend with that distributor?
I did have it cut out on me once since i last posted. I took it out for a 4 day camping trip and we ran it like we stole it all weekend, without a single hesitation. I took it out one day after that, and it stalled out on me once, I let it sit about 5 min, fired right up, and we were ready to go home anyway, so we headed back to the launch.
The only thing I can think about that particular run that was different is, i was letting my brother and son and wife trade off driving, and since they arent used to it, they were going slow, probably about 2200 RPM, just barely on a plane, for about 15 minutes. When I took over, I punched it good and drove it like I usually do, and about 30 seconds into my take-over is when it stalled. All I can think is, the way they were driving probably puts it under a lot more load than driving it faster, because it's not really out of the water, its sort of "plowing" along, and not running in it's optimum RPM range. I really wish I had taken notice of the temp when I took over, but I did not. I noticed when we stopped that the temp gauge was pegged, however I noticed later (since I was watching it carefully now), that as soon as you start it, it drops down to the 160 - 180 degrees range, making me think that with the engine off, it shows the high temp because the sensor is at the top of the intake manifold, probably where steam would accumulate when the engine isn't running...
Does that theory hold any water (so to speak)?