Could too long fuel hose cause fuel problems?

[WriterCJ]

Hi,

Quick question. I'm having problems with a 1989 Evinrude 20HP. It will start when primed but then quickly dies at idle and won't throttle up. There doesn't seem to be enough fuel getting to the engine.

I've checked all the external fuel connections for leaks / re-sealed them and all seem to be fine. O-ring in the quick-connector at the engine seems new / perfect.

Before I start pulling off parts like fuel pumps, etc. / pulling the boat out of the water, I was wondering could the length of the fuel line from the tank to the engine be causing problems?

I replaced a perished fuel line recently, and the new line is considerably longer than the one it replaced. Could that be causing problems preventing the fuel pump from drawing enough fuel into the engine?

We only have a few weeks worth of boating weather left in the south of Ireland before I'll be pulling the boat out of the water and I'll be getting the engine to a mechanic for a full service -- but would love to get to use her for that couple of weeks... especially as the mackerel are around at the moment.

Any advice / help / pointers greatly appreciated.

Cheers,

Calvin!

 

[kenmyfam]

Re: Could too long fuel hose cause fuel problems?

Was it O.K. before the fuel line change out ???
How much longer is the current line than the old one ??
Have you checked the fuel pump output ??
You need to get back to those mackerel !!!!

 

[oldcatamount]

Re: Could too long fuel hose cause fuel problems?

I have a 16ft boat with a 15hp motor and I put the gas tank as far forward as I could and it seems to work fine. I don't think it's the distance that matters as much as the height the pump can lift.

 

[ezeke]

Re: Could too long fuel hose cause fuel problems?

It's more an issue of how high the pump has to lift the fuel, but if the line is too long you may need to use line with a larger interior diameter, fewer bends and larger fittings. Generally a 20HP should do fine on 1/4" ID.

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Thanks for the reply.

It seemed to be running OK in a test barrel at idle, and seemed to throttle up OK in neutral (manually depressing the throttle linkage/lever) after changing the fuel lines, but I was afraid to try it under throttle / in gear when in the barrell.

So I decided to give it a try in the water. It's currently on a mooring so working on it means a trek down tot the seaside (seven or eight miles) and a row out to the mooring.

I discovered AFTER thinking it was all running OK that at some time in the past somebody had set the electric primer half-way between the standard and manual position :-(.

Bottom line now is that it seems to idle OK if the electric primer is switched to the manual position... but dies after about ten seconds when the primer switch is in its standard operating position (red lever pointing back over the solenoid towards the rear of the engine).

I'm very green to outboards, but it does seem to be a fuel starvation issue.

A friend who's a very good mechanic (he's an electrical engineer and works on Formula One racing engines for Cosworth in the UK) overhauled the carb and checked all the electrics/ignition for me recently -- so pretty sure they are all OK.

The fuel pump is probably the prime suspect here, but I'm keen to eliminate simple (less expensive?) stuff first -- hence my question about the fuel line.

Going to look for potential problems in / around the fuel tank connectors, fuel pickup, etc. next after reading a few posts around the topic here. Start with stuff OUTSIDE the engine (tank / lines / etc.) before I start dismantling stuff under the cowl.

Mackerel may be getting a bit of a reprieve over the next few weeks while I get this sorted :-(.

Will get the engine to a marine mechanic for a complete overhaul as soon as I can -- but all the local ones are too busy to look at it for at least a month... hence my frustrating attempts at DIY diagnostics.

Thanks for your help.

Calvin!

 

[ezeke]

Re: Could too long fuel hose cause fuel problems?

Unless you are manually providing the fuel pressure, the problem is probably the clogged high speed jet in your carburetor and not the fuel pump.

The primer solenoid does not create fuel pressure, it's just a valve, so the fact that operation improves with it open indicates that the fuel pump is working and that your carburetor is the problem.

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Thanks for the pointers everyone.

I will be down at the boat tomorrow and will check the fuel tank and lines for potential problems / air leaks to eliminate that side of things.

I was wondering about it being the carb. Maybe it got gunked up after the last clean, although the engine was started and run in a barrel intermittently in between (it wasn't sitting completely idle for long periods).

How difficult is it to remove the carb from the engine -- is it something I could do at the boat, then bring the carb home to dismantle/clean before re-fitting it back on the boat?

Tempted to just pull the whole thing back out of the water and bring it home to work on, but in the process of fixing up the trailer now the boat is off it, so that will have to wait a bit.

Sorry if my questions are a bit on the basic side... this is all new to me. Great to learn new stuff though.

NB: Nobody warned me about how distracting / obsessive / addictive this stuff could become before I started. Now spending ridiculous amounts of time reading up on outboard stuff instead of doing real work :-(.

Thanks a lot for the help guys!

Cheers,

Calvin!

 

[Rick.]

Re: Could too long fuel hose cause fuel problems?

"A friend who's a very good mechanic (he's an electrical engineer and works on Formula One racing engines for Cosworth in the UK) overhauled the carb and checked all the electrics/ignition for me recently -- so pretty sure they are all OK."

Well he might be acceptable to formula one drivers but that won't qualify him to work on a jewel like and OMC. LOL ( he sounds more than qualified)
I would agree you should pull the carb. and re-clean and make sure the float/needle mechanism is working correctly. You can remove it and take it home. Best of luck. Rick.

 

[Tim Frank]

Re: Could too long fuel hose cause fuel problems?

The o-rings in the quick-connects can "look" OK but still be a problem. They are cheap and easy to replace.

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Thanks Tim,

Replacing the o-ring in the quick connect is on my list .

 

[Tim Frank]

Re: Could too long fuel hose cause fuel problems?

Both ends...

 

[Craig-]

Re: Could too long fuel hose cause fuel problems?

Once primed, a longer fuel line will not require any more suction than a short one, as long as it has the same rise and no air leaks. The simple test would be a small test tank hooked up close to the motor, if she runs with that, your new setup most likely has an air leak or more rise than the pump can lift.

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Thanks guys,

The line only has a quick connect on the engine side -- the other is clamped to the fuel tank -- so only one o-ring to replace.

Will try and get hold of a different / new fuel tank and test with that. At least that will eliminate a whole lot of things in one fell swoop. Actually investing in an additional tank and line may be a good move in any case.

Cheers,

Calvin!

 

[Craig-]

Re: Could too long fuel hose cause fuel problems?

Thanks guys,

The line only has a quick connect on the engine side -- the other is clamped to the fuel tank -- so only one o-ring to replace.

Will try and get hold of a different / new fuel tank and test with that. At least that will eliminate a whole lot of things in one fell swoop. Actually investing in an additional tank and line may be a good move in any case.

Cheers,

Calvin!

Let us know the results.

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Didn't get down to the boat today . Rain and wind made it impractical.

Will try and get to it tomorrow evening, weather and kids permitting! Will certainly keep you all posted. It's great to have a bit of a support network when you don't really have much of a clue what you're doing ;-).

Cheers,

Calvin!

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Okay, latest update:

Was down at the boat tinkering with the engine for a couple of hours yesterday. Went through the fuel hose and tank... all good. Quick connector... all good. Fuel pump, as far as I can tell... all good.

I changed the spark plugs for new ones, and there's a good, hot blue spark from each. Have no way of doing a compression test while she's on the water... will get all of that done by the mechanic once she's back on dry land. Can "feel" what seems like similar pressure if you hold your thumb over the spark plug holes and crank it (I know... useless test, but at least it tells me there's something happening in there).

Bottom line: once primed she starts fine, idles for about 10-15 seconds, then gutter and dies. I can keep her going for a bit longer by repeatedly pumping the key to fire the electronic primer solenoid, but eventually she always dies.

Giving her a bit of throttle manually as she idles caused her to rev a bit, and then die immediately.

After loads of faffing about I finally gave up, took off the carb and brought it home (what idiot hid the nut to get the carb off right in behind the starter motor?).

Took it apart and cleaned it up last night. Still "looked" spotless from the last time it was cleaned, but...

...there was some unidentifiable gunk clogging the high-speed jet AND the little channel that sits just beneath it and exits opposite the drain plug.

I think there are a couple of other problems too.

I don't have a carb repair kit, but have requested one from a local dealer and will fit all new bits and bobs as soon as I can. Most of the existing gaskets and seals LOOK perfect, but there is one washer/gasket that's definitely borderline around the head of the slow speed / idle needle valve.

What happens if there's air getting in through there...? Guessing that could be causing an idle problem, right?

While I'm waiting for the carb repair kit I've re-used existing seals and gaskets to put the carb back together. Will put it back on the engine and see how she behaves over the next day or two... but not hoping for too much until I get the carb kit with all the new bits in.

One other problem I noticed... the adapter that screws into the carb to hold the slow-speed needle valve won't tighten in properly. It's as if the thread is burred either on the adapter (which looks OK) or on the carb itself.

Hoping it's the former... because otherwise I'm going to need a new carb :-(.

Have tried to get everything to fit and seal as best I can for the moment, and will give it a try.

Will be putting the cleaned carb back on later today or tomorrow. Will keep you posted... and given that the carb is a bit dodgy if I go anywhere in it I'll be keeping the 5HP Seagull (1974 ) auxiliary engine fuelled up and ready to go, just in case.

Thanks for all your help and advice.

All the best,

Calvin!

 

[Craig-]

Re: Could too long fuel hose cause fuel problems?

Did you add a water separator filter to your new line setup? The primer bulb in the right direction? Try a test tank?

 

[Tim Frank]

Re: Could too long fuel hose cause fuel problems?

Is this motor new to you and and/or are new to motors?
Reason I ask is that there is one very item you could check....almost trivial....not likely the cause/solution....but I didn't see it mentioned so far, so maybe...

If it is not new to you, and has operated satisfactorily previously, this probably won't help....but....

Tank venting. Is there a vent screw on the tank cap...and if so, is it open?

 

[WriterCJ]

Re: Could too long fuel hose cause fuel problems?

Thanks Craig and Tim,

No -- I haven't got a fuel / water separator installed, but I don't think water in the fuel is causing the problem, and yes the primer bulb is in the right direction.

Yes the engine is new to me, and yes, I am new to outboard motors.

Yes there is a vent screw in the top of the tank, and yes it is open and venting properly. First thing I checked.

At this stage I'm fairly sure the main issue is (was?) the carburretor. Have cleaned thoroughly and re-assembled, but without a carb repair kit. Waiting on one of those and will re-do it once it arrives.

Meanwhile I'll re-fit it tomorrow and will give it another try.

Thanks for your help.

Cheers,

Calvin!

 

[jtexas]

Re: Could too long fuel hose cause fuel problems?

The parts you re-used -- if Formula1 Guy installed 'em very recently, they're more than likely good to go, IMHO.