Morphing Starvation

[chanlmee]

Hello everyone,

I've just acquired a lovely Atomic 4 engine and already I'm making a mess of the lovely thing. I'm here to change that and hopefully have her running smoothly! I've run into what I believe to be a fuel starvation issue and I would be grateful if any of you can offer your insights on next steps. Thanks in advance!

Suspected Fuel Starvation Issue:

Background: C&C 27 Pegasus - Well Maintained Atomic 4 Engine - New Owner

June, July: ran engine for very short periods (5-10mins) with choke mostly on – believe it was because the fuel was old (about 1-2 years old, had stabilizer in it, about 5 gallons), never had issues starting nor running (so long as choke was on). When choke was off engine quit.

July 23: New fuel – 10 gallons added (did not add anything to fuel). Would no longer run with choke on. Ran fine without the choke. I took this as a good sign. Motored the boat for 2-3 hours without any issues.

Aug 1: Started engine easily but forgot to turn fuel on! Ran fine for about 30 seconds - 1 minute then fuel starvation killed engine. Realizing my mistake I opened the fuel valve and tried starting the engine but no luck. I also tried to get it to “re-prime” itself by running the engine with quickstart spray into the carb for a few about 10-15 second bursts. No luck. Most of you are probably shaking your heads by now!

I decided I had to manually reprime the fuel line so disconnected the fuel hose leading into the electronic fuel pump to suck the fuel out (I thought perhaps I had an air lock or something). Instead of sucking out I ended up pumping air into the line or blowing outward. The manual pump I had in my hands was reversed (dummy!). However I realize now the gas cap was sealed so I’m not sure I actually did anything. Realizing I had the pump setup wrong I corrected the issue and sucked out fuel with the hand pump. With the fuel draining into the bilge I reconnected the fuel line into the electric fuel filter.

When all was tight I rinsed out the bottom of the boat and general engine area to remove the spilled fuel. I pumped the bilge, aired the fumes and started the engine. Engine started easily and ran smoothly for 5-10 minutes. My problem was resolved! It was late and I left for the night. All was good right?! Wrong…

Aug 6: Started engine easily, engine operating well, as I was leaving the marina the engine started choking, played with the throttle and was able to clear the marina. When under load the engine would die out after anywhere from 5-20 seconds. If I went into neutral the engine idled nicely. As I was midstream in leaving the marina I continued to restart the engine 4-5 times to move Pegasus out. I reverted into neutral when I heard the engine starting to die but sometimes I was not quick enough. When the engine was not under load (not in gear) the engine would run smoothly. When I put the engine in gear it would eventually starve and stop. Hours later upon return I restarted the engine just for kicks and it ran for about 1 hour under load at about 3.5 knots (low RPM). I thought this was fortunate as it was 11pm and the winds were dead. (I didn’t have to crawl into the dingy and row Pegasus into her slip…..phew)

Current Situation!
Aug 12: After reading and discovering these forums I went back to the boat and added 5-6 ounces of MMO and another gallon of fuel. The engine starts up everytime but the starvation has morphed. Now she doesn’t need to be under load to die out. Even in neutral she eventually starves. I tried to listen carefully and here is what I recorded:

-Can start easily/repeatedly on choke or without the choke.
-Will run smoothly at idle for random times between 15 seconds to 2 minutes before a soft gentle shut down occurs.
-When idling the engine has a constant rhythm/ rpm
-When I try to throttle up – sometimes she responds and the rpms increase and sometimes she starves
-Eventually she starves no matter what combination of choke/ throttle is provided
-Soft gentle shut down

I’ve included a picture: In line filter between electric fuel pump and carb

I’m not sure what to do next! I’m thinking about blowing out (this time with the gas cap off) to move any particles potentially obstructing the inflow from the tank and then re-priming the fuel line, this time letting it drain well to ensure solid flow. I wonder if I somehow water got in/near the carb (perhaps through the flame arrestor housing?) when I tried to wash out the gas?? I’m hoping there are less invasive ways to trouble shoot this as I think the engine was well cared for despite the fact it wasn’t used for a season before this year.

I’m somewhat at a loss and welcome any advice. Thank you in advance!

[ndutton]

For starters I'd set up a temporary fuel system with a portable outboard tank fed directly to the fuel pump inlet and fresh fuel. If that solves the problem as I expect it will we can dig into the onboard fuel system but we need to know the temporary tank works first.

If it doesn't, we'll look elsewhere.

[joe_db]

Vacuum and pressure gauges are your friend too. You need to know what is happening.

[67c&ccorv]

In all of the above you never mentioned whether you checked the oil level or when the oil had last been changed.

For a motor that sat for a year I would do both (check and change oil) before attempting any further startups.

Just saying...

[smosher]

I would do as others have suggested, change the oil, run the engine on a temp tank. I would add changing the filter in the picture, a polishing filter, clean out the pump filter, and clean the carb. Sounds like there's crud in the main jet, What kind is it fixed or adjustable ?

Steve

[CalebD]

Do the cheap stuff first.

Did you mention if it has electronic ignition or points?

Do the cheap and easy stuff first:
-Try a fresh fuel supply as Neil suggested.
-Change the engine oil at least once - also mentioned
-Drain the carburetor by removing the lower aft bolt or main passage plug. -Catch the gas coming out in a clean cup and inspect it for water or crud.
-Check or replace distributor cap, rotor, points, plugs and wires

If no satisfaction at this point:
-remove and re-build/clean carb
-inspect exhaust system for obstructions
-?

[JOHN COOKSON]

Rich Or Lean?

-Can start easily/repeatedly on choke or without the choke.

IMO this indicates you are running rich.
The A4 usually needs brief full choke to start even when warm.
When starting cold needs a longer period of full and partial choke.

Being able to start your engine easily with no choke isn't normal.

To rich or to lean will produce the same symptoms.
Are the plugs wet with fuel after a shut down?

TRUE GRIT

[Bold Rascal]

Welcome Chanlmee

Some great suggestions here, Just an adder to Niels suggestion.

You can also bypass the fuel pump and take your temporary outboard fuel take and squeeze pump hose directly to the fuel inlet at the carb. A good squeeze every so often (30-60 seconds?) will keep the lil beastie running.

Be very careful handling gasoline, No spills, no sparks and keep everything well ventilated.

[chanlmee]

Thank you all so much for your feedback and suggestions. It's rained a lot here so between working and the rain it's taken me some time to actually get back to the boat.

I've got great news! I did as Neil suggested and rigged a fuel can with an 8 foot fuel line directly into the electronic fuel pump. She started an would not quit no matter what I did! She responded to increases in throttle and also an ultra low idle. I ran her for about 20 minutes total with a couple of test starts in between - no problem. Regarding the choke I think its set right. When cold the choke is required. When the engine is warm I don't need it and that makes sense.

I drained some of the gas from the fuel tank (as I told you all I'm a starter mechanic - aka not much of one) and was surprised to see that it's a gravity system. All I had to do was open the valve and presto I had fuel draining into my very clean glass cup. I inspected the fuel and it looked perfect. I could not detect anything not uniform in it (so I poured it into my truck ... I hope I don't have to make a trip to my mechanic soon!).

That gas is brand new from my boat club. I just pumped it in this last month so I'm not sure whats going on! I did notice that though the gas poured out easily the pressure was not as high as the rigged gas tank. The rigged gas tank was 2-3 feet higher and didn't pass through a copper line. Could it be there is Ethanol in the fuel? Perhaps the fuel is contaminated. I did pour those 5-6 ounces of MMO into the 10 gallons of fuel. The MMO is about 2 years old? Perhaps there is moisture/ water buildup in the tank?

Next steps?

1- Drain all the fuel out of the tank?
2- Try to "clean" the fuel tank with something? Ideas?
3- Pour in a new gallon of fuel (no additives) from another source (i.e. 91 Octane from a gas outlet - not the boat club - I will call to find out more)
4- Try to reconnect the fuel tank and try running the engine?
5- Could it be the electronic fuel pump is pumping but not as strong as it used to be and the additional pressure is helping it provide a constant flow?

Any other thoughts?

ps. I checked the oil and though it sat a season it was pure and brand new at the beginning of the season so I don't think I will change it right now. It only has a few hours of use (I don't motor much).

I tried to find a polishing filter as per the specs in this forum but all I could find was a Sierra plastic thing (10 microns) and I wasn't comfortable replacing the filter I have on with something else. I guess I will order a couple from MM and keep them for future replacements.

[chanlmee]

Here are some pictures of the fuel tank and connection from the copper line to the electronic fuel pump.

[ndutton]

Now we're gettin' somewhere

Okay, we now know for certain you have a fuel system problem ahead of the pump so that's where we need to look, you've successfully demonstrated the engine works fine. Here are the possibilities and as is my way, I recommend getting aggressive here for a reliable resolution that should last for years:

1. Bad fuel - I don't fuel up at the fuel dock, prefer jerry cans as you're planning. The fuel dock doesn't pump enough fuel for my taste which increases the chance their tank is full of nastiness of which I'll have no part. edit: high octane fuel is a waste of money. It is commonly accepted here that our low compression engines do not benefit from higher grade fuels.
2. On board fuel contamination - you report clean appearing fuel but I would still replace the O-ring on the fuel fill deck plate. Where's the harm?
3. Fuel tank vent obstruction - needs to be checked, suggest removing the vent hose at the tank and blowing through it. Any difficulty or backpressure and I'd replace the hose and the vent fitting.
4. In tank fuel pick-up tube obstruction - check for a screen at the bottom of the fuel pick-up tube. If one is there, get rid of it. Blow through the tube to make sure it's clear.
5. Fuel hose deterioration/obstruction - I'd simply replace the fuel supply hose and be done with it.
6. Fuel filter obstruction - time for a new element at a minimum (10 micron per Don's recommendation), perhaps an entire new filter unit.

And since you've determined your fuel system gravity feeds, an important safety item is a fuel shut off valve immediately ahead of the carburetor. This valve should be closed any time you leave the boat. Any debris in the carburetor float valve and you risk a potentially dangerous fuel leak.

[Dave Neptune]

Hmmmmmmm

chanlmee, welcome to the forum. From what I have read of your chronological information I'd say it is very simple.
First don't touch the ignition at this time as it seems to be working fine and it can be tuned later.
Your symptoms do indicate to me that the carb is not working properly due to a blockage inside or a fuel delivery issue. A fuel preassure gage would let you know if you do indeed have adiquit fuel preassre being delivered, it doesn't take much!!!!
I would remove the carb and clean and blow it out good, unfortunately you will need a kit to insure a good seal between the halves of the carb. Pay particular attention to the small ports around the butterfly as those are the idle ports and they are small and easily plugged. You can poke at them with a piece of copper wire. Remove all the jets and orfices so you can "blow out the passages". Then reinstall with a fresh polishing filter. I think you will be suprised by the results.

Dave Neptune

[chanlmee]

Morphing No More

So I did as you suggested Neil and rigged a temporary fuel tank. As I reported earlier the engine is not starving anymore and runs smoothly.

Before draining the gas tank of the fuel I just pumped in I just had to find out if it was the fuel or not. So I rigged a 2nd temporary gas tank and connected that to the electronic pump.... It ran smoothly as well. Not a problem and no interuptions no matter what I did.

So I reasoned the fuel is not the problem. I assumed it was then the tank and or the line. So .... I just had to do it ... I reconnected the gas tank and line back on to the electronic fuel pump. I assumed we would once again have the engine running and then quit... but it never happened. The engine would not quit and was running smoothly.

There are 2 things I did which I neglected to mention and could have been the cause of the original dieing out of the motor.

1- I could not resist "blowing out air back into the fuel tank to clear the line and push away any possible sediment which might be blocking the fuel going down into the line.
2- I also replaced a connector of an electrical wire. Its the blue connector within the red circle in the picture I included. Not sure what that wire was for but making a better connection there may have helped solve the problem.

Other than that I don't know why the engine isn't quitting anymore but one thing is for sure! I'm bringing on board my temporary jerry can in case it repeats itself.

Thank you to all for providing your insights. It gave me what I needed to try to resolve the problem myself.

Cheers,

[ndutton]

That's the sender wire for the oil pressure gauge, has nothing to do with engine performance.

Okay, you got her running and have a contingency plan if the symptom repeats. That's a major stride in the right direction.

Looking at your picture, I'd like to suggest a project for the not-to-distant future: relocation of the oil pressure sensor array to a nearby bulkhead. You have a lot of stuff hanging on a soft brass 1/8" nipple threaded into a vibrating engine. This is a potentially catastrophic problem waiting to happen that could destroy your engine.

I had the same array and relocated it with a short length of 300 psi hydraulic hose I bought at NAPA. Be sure to take a ground wire to the array or the senders won't work.

[sastanley]

Neil, I am wondering if the blue line is feeding the oil pressure sensor and maybe looping out of the picture and back to the oil pressure safety switch (OPPS)..if that line had a bad connection,and the OPPS was not receiving proper readings, maybe the OPPS turned off the juice to the fuel pump?

I agree with Neil that you have a lot of stuff (three senors) physically hanging on a fragile connection...I'd relocate all of the sensors to a firm mount as well. You can pick up a cheap 'hard' copper kit at a local auto parts store to feed the sensors and switches.