Hard to start after a few days?

[sail_flathead_lake]

Hi all,

My new-to-me Tartan 27 has an issue that my other A4 never had: If the engine sits for a few days, it becomes hard to start. When this happens, it sounds like it's not getting fuel. I have to crank it for several (5 - 10) ten second tries before it will start to sound like it's getting fuel, and then once it catches it runs great. If I've started it the day before, it starts right up, first try.

It's not a spark issue as when this happens I've checked spark and found a healthy spark. Is it possible that the fuel in the bowl is leaking out over the several days that the boat sits? The fuel pump is electric, with OPSS, and there is a fuel filter (spin off type) on the line. Full disclosure - the gas is a couple of years old, but as I mentioned, it runs like a champ once it starts. Also, it always starts right away if I ran the motor the day before. It's only after sitting for a few days that it gets hard to start. Yes - I do close the raw water intake when cranking under those conditions.

Thanks!!!

[JOHN COOKSON]

I've noticed this phenomenon too. The longer the time since the last start the more difficult it is to start.
I always attributed it to the fact that I have the idle set as lean as possible.
Maybe I should check the timing sometime? Or what???

TRUE GRIT

[BunnyPlanet169]

Thinking out loud, I can imagine two possible causes, but this is not from hard experience.

First, it's plausible that some longer duration off time, the carb takes longer to get 'wet'. Fuel should be in the bowl, but maybe it does evaporate slowly? Fuel lines may or may not drain back to tank, etc. Choke adjustment could come into play.

A second thought is that with an OPSS, after an extended off period, it may take longer for oil to fill and pressurize in the oil galleys. This would tend to amplify the first scenario....

??

[JOHN COOKSON]

Don't think it has anything to do with the OPSS. The carb bowel should be full of fuel from the last run and give ~45 seconds of run time even if the OPSS is not functioning at all.

Maybe has to do with updraft carbs? Dave N. are you logged on?

TRUE GRIT

[Mo]

Very small diaphragm leak in a manual fuel pump or a very small leak at a joint such as fuel filter, fuel filter seal etc. My guess would be a pump leak allowing a little air in...very common with diesel engines. Generally a sign of the pump on the way out.

[Dave Neptune]

As the engine sits some of the fuel will evaporate, a bunch at first due to the heat in the engine dissipating and will continue when the engine cools. An updraft carb is far more susceptible to lean starting causing longer cranking times. This is a good thing as it allows for the oil pump to get some oil where it needs to be before igniting into life.

Yes a really lean idle will take longer and that to is still a good thing.

The fuel lines draining back and or the "OPSS" needing a few more spins to "close" will also add time for the "start". I consider this all good. Many "hot rods" with really powerful engines have a start switch and ignition switch to do the same thing. Some engine we'll crank for 15~20 seconds before hitting the ignition switch~this just to be sure oil is in the right places~a good thing!

Any time I hear someone mention that there A-4 instantly starts I think the idle is way to rich or the floats are way to "high", and wait to hear of plug fouling. Any engine with an updraft carb (no acceleration pump) SHOULD take a few more turns to get fuel into the combustion chambers to get it lit!

Dave Neptune

[edwardc]

I had a Honda Civic that did the exact same thing. Would start fine if run daily, but a hard start if left over a weekend. Problem turned out to be sticking valves. The cure (which took some time) was to add MMO to the oil. I went pretty heavy and replaced a full quart of the oil with MMO.

[Skywalker]

Dave, well I'm that guy with the A4 that starts right up. She even fired up within a couple of seconds after being winterized and then sat for 7 months. Guess I'm a little rich!

Something else to add to the list.

Chris

[hanleyclifford]

I have ignition on an OPSS. I don't want the engine to fire until minimum oil pressure is established.

[capnward]

slow starting when cold, probably too lean

Hi Flathead Lake Sailor, with a Flathead engine,

Since your engine runs fine once it starts, there's probably not much water in the gas, or crud restricting the fuel line or carburetor orifices/jets, or a problem with the fuel pump. Although, I have a mechanical pump, so I don't know about OPSS. I suspect the timing, or the fuel/air mixture being too lean, or the choke adjustment as the likely culprits. Having a fuel pressure gauge in the line just before the carb could tell you if you have a leak in the fuel line, if the needle drops after the line is pressurized. That and wet hoses. (Shudder) Be vigilant! Always sniff for gas. Good Luck.

[capnward]

If longer cranking times are good, then...

My A-4 starts instantly without choke once it's well warmed up. I like it that way, and don't seem to be fouling plugs. I think as long as it's been running and warmed up, the oil is where it needs to be. I tend to ignore the oil pressure gauge as long as the dipstick looked OK before I left the dock, but I'll watch it more often now.
This discussion about longer cranking times being a good thing has got me thinking:
1. I have a mechanical fuel pump, and no oil pressure alarm. I think now I should get one. I have a temperature alarm, which might prevent me from seizing up the engine as it overheats from an oil pressure loss, but too late to prevent damage.
2. I had assumed an OPSS was something you use with an electric fuel pump, to turn off the fuel pump when the oil pressure got too low, but now I gather that it turns off the ignition, and also prevents the engine from starting until oil pressure is high enough. Is that right? Since I have no OPSS, and can start the engine before the oil pressure is optimum, then in future when the engine is cold, I should deliberately turn it over a while before engaging the starter, to get the oil pressure up a bit, and oil distributed better in the engine. This would be counter to what I have been doing. When the engine has been sitting a while, I sometimes work the bail under the mechanical fuel pump to pressurize the line, and fill the carburetor bowl. The idea was to reduce the cranking time, the wear on the starter, and the battery power involved. Also to avoid the dreaded water in the cylinders from over-cranking with the water on. She starts usually after a few seconds of cranking that way, choke on of course. But now I learn that it's actually better to crank for a while before firing up, to get the oil "in the right places."
This makes sense. I've been thinking that the most damaging thing I've done to the engine is start it up in the spring after 4 or 5 months of inactivity, without putting a bottle cap full or so of oil in each cylinder and letting it soak down around the rings for a day or two. This year I did the oil (MMO) in the cylinders trick, and felt better about it. Did I use enough oil? Would motor oil be better than MMO for this? I used too much last year and started it hours later, too soon I think, and it just pushed the oil into the carburetor, not starting. The red drips from the carb indicated my mistake. This year I used less MMO and waited a few days before starting. Is a day or two of soaking enough? Ideally I would run the engine regularly through the winter, but I am living 5 hours away. I don't winterize, the boat being where the water is 42 degrees, and keep the boat heated a bit, under a cover.
So how much cranking should be necessary before firing, to get the oil pressure up? What is the minimum oil pressure? At what oil pressure does the OPSS let the ignition work? Can an OPSS work with a mechanical pump? Can I just crank (water turned off) until the oil pressure gauge reads say, 40, then turn on the ignition? Will the oil pressure even reach 40 just by cranking? Or is it adequate to just crank long enough to pump gas from the tank, pressurize the fuel line, and fill the carburetor bowl, in which case I can just start the engine normally?
Too many questions, I know. Thanks for any input.

[JOHN COOKSON]

My advice to the OP would be to try a tad richer in the idle, maybe a quarter turn on the needle adjustment and see what that does.
My A4 always starts on the first or second 8-9 second burst of starter even after sitting a couple of weeks.
BTY SFL is your start battery loosing charge after sitting for a few days?

TRUE GRIT

Edit: Are the battery cable connections hot & ground clean and bright?

[BunnyPlanet169]

1. I have a mechanical fuel pump, and no oil pressure alarm. I think now I should get one. I have a temperature alarm, which might prevent me from seizing up the engine as it overheats from an oil pressure loss, but too late to prevent damage.
2. I had assumed an OPSS was something you use with an electric fuel pump, to turn off the fuel pump when the oil pressure got too low, but now I gather that it turns off the ignition, and also prevents the engine from starting until oil pressure is high enough. Is that right?

1) I think everyone would suggest it's cheap insurance, and you can install it with an audible alarm, or go full boat with the EWDS....

2) Not exactly. The OPSS is required by USCG if you install an electrical fuel pump. It's less about monitoring oil pressure than providing a signal that it's OK to start pumping fuel. Without the electrical pump, you could wire it in so that you could crank the engine, but the switch controlled voltage to coil + preventing spark before the oil pressure was available (Hanley - is that your circuit?). It's an interesting application instead of just a warning buzzer or light.

The MMI switch says 6psi +/- 2psi to close. IIRC, the MMI manual suggests you should be able to get maybe 20psi from cranking alone.

I don't know that long cranking for oil pressure is advantageous beyond, say, 5 seconds? That's 130 amps in a circuit somewhere.... I don't know that the OP actually has a problem at 5 - 10 seconds. There have been times when I would have considered a predictable 5-10 seconds very good news.

[hanleyclifford]

First of all, I don't think you have a real serious problem, but if you are concerned about getting fuel to the carb as soon as you start cranking you could run a wire from the "R" terminal on the solenoid to fuel pump+. It would also be a good idea to have a fuel pressure gauge right at the carb.

[ndutton]

Please read John Cookson's post (#4 in this thread), he is spot on. Fuel pump operation during cranking should have nothing to do with starting. If it does your carb bowl is emptying during layoff and that needs to be dealt with directly rather than with another band-aid workaround.

The OPSS is there for safety. It prevents the electric fuel pump from operating when the engine is not running. I'd like to know what the USCG thinks about defeating the OPSS during cranking by using a solenoid terminal originally intended for an entirely different purpose (ballast resistor bypass).

edit: if I read between the lines I think the USCG is OK with electric fuel pump operation during starting (but it's still not necessary). I interpret when the engine is started as during starting.

§ 183.524 Fuel pumps.
(b) Each electrically operated fuel pump must not operate except when the engine is operating or when the engine is started.