Runs for a few minutes, then dies...

[hsagman]

First of all a big thank you to the folks to helped me get it running in the first place. I had no compression, got advice from this forum and fixed the problem! (It was stuck valves.) You guys are great.

So, here's the next phase. I got the engine running. It runs for about 3 - 5 minutes then dies. If I give it gas, it dies quicker. Here are the hints I'm working with: 1) There seems to be a small water leak at the top of the wrapped exhaust hot pipe that comes out of the manifold. 2) When the engine stops, there is a bit of smoke drifting up from the crack between the head and the manifold. Could either of these have anything to do with the problem, or should I be looking at a potential carburetor issue?

PS I have one of those systems that uses antifreeze to help cool, and there seems to be plenty of water coming out the back when the engine is running.

Again, thanks in advance for any suggestions. Hank

[Mo]

If you have a digital camera with a video option get us some video...include smoke and steam. Personally I'd like to hear how it dies and see the smoke and steam you are referring to. If you could do that it would be a great help with regards to steering you in the right direction for a fix.

I take the video, upload it to youtube and then post the link here on the forum.

[Administrator]

Electric fuel pump?

Bill

[ndutton]

The timing strongly suggests start-up with a full carburetor bowl and then depletion to the point of fuel starvation. My experience is the A-4 will run at idle for somewhere between 1 ~ 2 minutes on a full carb bowl with the fuel supply shut off so @3 minutes I think you're getting some fuel pumped but not enough to keep up.

I'd examine the entire fuel delivery system starting at the carburetor and working back. A fuel pressure gauge at the carburetor inlet will point you either toward the carburetor or the fuel supply.

[hsagman]

Some answers...

Hey thanks guys. Here are my responses to your reply's

Mo, I will take some video. Good idea.

Bill, yes it is an electric fuel pump. Any suggested way to check if it's working properly?

ndutton, I don't have a fuel pressure gauge, but I'm willing to get one if they're not too expensive. What kind of readings should I be getting?

Thanks, Hank

[ndutton]

I don't have a fuel pressure gauge, but I'm willing to get one if they're not too expensive. What kind of readings should I be getting?

We'd expect somewhere between 2~4 PSI. The EWDS warning system has a fuel pressure trip point of < 1 PSI. Some of the guys have a preferred fuel pressure gauge (Mr. Gasket??) that isn't expensive at all. I'm sure they'll be along to offer more specifics.

Shameless plug:
The Holidays are just around the corner so when considering how you'll show your appreciation to your boat for the pleasure she provides, MMI's Engine Warning and Diagnostic System (EWDS) provides real time fuel pressure monitoring with a cockpit display and audible alarm.

[Al Schober]

Hank,
I have to agree with Neil's diagnosis of fuel starvation. The leaks are other issues. I've just gone (am going?) through this - you may want to browse through the thread 'Carb Overflows'. That pressure gauge is from eBay - about $12, works great!

[Marian Claire]

Bill, yes it is an electric fuel pump. Any suggested way to check if it's working properly?
Easy way to check pump performance is to bypass the OPSS, a short wire with alligator clips works well. Do the clips/bypass first so you do not create sparks. Disconnect the fuel line where it enters the carb. Hold the hose over a container, a clear and clean container works best as it allows you to evaluate the quality of the gas as well, and turn the key to the on position. This will energize the pump and you should have a strong steady flow. Do this for just a few seconds and turn the key off. Never leave the key in the on position for long when the engine is not running or we will be dealing with a coil issue.
Dan S/V Marian Claire

[JOHN COOKSON]

Personally I'd like to hear how it dies and see the smoke and steam you are referring to. If you could do that it would be a great help with regards to steering you in the right direction for a fix.

I'd like to hear how the engine dies and restarts.

When the engine dies does it:
Stop suddenly like the key has been turned off?
Sputter to a stop like the engine has run out of fuel?
Labor to a stop like it is overheating?
If none of the above then you describe. A video would be helpful.

When you restart the engine:
Does it start normally without any delay?
Have to sit for a while then start normally?
Grind on the starter for a while then it starts.
None of the above.

TRUE GRIT

[warefuller]

Runs for a few minutes, then dies

I had the same problem. Turned out to be junk on the fuel pickup screen in the tank. Other potential causes:
1. Weak fuel pump.
2. Float valve not opening enough (float set too high, dirt in the float valve)
3. Partial blockage in fuel line.
4. Clogged fuel filter(s).
5. Clogged idle orifice in carb.
6. Choke closed (unlikely).
7. Ignition (unlikely, since nothing warms up much in 2-3 minutes)

Good luck.
Ware

[hsagman]

OK thanks guys...

Sounds like I need to check out the fuel delivery. I'm going to do that this week and get back to you. Thanks again. Hank

[lat 64]

Hank,

Congrats on saving a few thousand dollars!

You'll now be chasing several problems on all the deferred maintenance of your A-4. Don't get too discouraged.
You are now already in a position to help other a-4 owners that find this forum. Go ahead and write a final post in your first thread so the story has an end and someone can read it in the future and benefit from the advice given/taken.

cheers,
Russ

[hsagman]

The latest...

Hello all. Here’s the latest. When I went down to check out the fuel system, here is the series of events.


1) Wouldn’t start. The valves were stuck again. Unstuck them.
2) Started ran for about 5 minutes then died as if someone turned off the key.
3) Disconnected fuel line to electric water pump. Fuel coming through fine.
4) Took the bottom of the electric water pump off. Didn’t find any filter (I thought there was supposed to be one). Put it back on.
5) Disconnected fuel line from water pump to carburetor at the carburetor. Fuel coming through there also. Didn’t have the engine running at this point but fuel was pouring out. Reconnected fuel line.
6) Went to start the engine and valves were stuck again. Unstuck them.
7) Engine ran great. This time longer, at least 10 minutes. Then started to lug and clank a little and finally died.
8) I didn’t try to start it again as I was running out of time.

Any ideas on why the valves keep getting stuck. In fact, it sounded like maybe one of the cylinders was freezing up as the engine was running. Is it possible for the vales to start sticking while the engine is running?

I took some video of the engine dying. Is there a way to upload on to this forum?

Thanks in advance for your help!

[hsagman]

Videos

Here are links to the videos I took of the engine dying and smoking.

This one shows the engine starting to labor and die.

https://vimeo.com/111291531

This one shows the smoke coming from the manifold.

https://vimeo.com/111291529

[Mo]

Here are links to the videos I took of the engine dying and smoking.

This one shows the engine starting to labor and die.

https://vimeo.com/111291531

This one shows the smoke coming from the manifold.

https://vimeo.com/111291529

Sounds like fuel starvation to me Harry. I think Dave mentioned a fuel pressure gauge. Good idea and see what you get. If you have good pressure then check the carb.

The most likely cause of something like that could be, as mentioned, float setting in the carb or an air leak in the system. Sometimes filters will have a bad seal and allow air to enter; sometimes a chaffed line; sometimes the pickup tube can have pin holes in it.

Something you could try is add gas to your tank and run the engine...if it doesn't shut down anymore you pretty much know you have pin holes in the pick-up tube.

The others will chime in and have some good ideas for you as well.

Second video: smoke; just likely the manifold gasket needs replacing....can even try retorqing the nuts.