GFP 40+ starts but won't get going

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Shamba
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Location: South Devon

GFP 40+ starts but won't get going

Postby Shamba » Thu Jan 07, 2016 6:34 pm

Hi,

This may be stale fuel but I wanted to check to see if there was anything else I should be looking at.

A classic story of a spares or repairs ebay purchase that sooo nearly runs.

The motor starts in a bin but never really gets going and stops after 15 seconds or so. I've replaced the plug, cleaned and gapped the points and stripped, cleaned and rebuilt the Bing carb. Had a few backfires, did the points again but more carefully and once flooded using the tickler it will start but struggles and then stops so I was thinking fuel starvation (cos it starts again when I get it more fuel by tickling again) or back pressure so I emptied a load of water from the bin to restore proper immersion levels with no effect and then I wondered about stale fuel. At this point i knocked it over (curses) broke the clamp screws which I've now replaced. Cost of parts to date now equals the very reasonable £35 I paid as a non-runner.

Why do I suspect stale fuel? The only fuel I had in a can was for the (4-stroke) lawnmower and was about 6 weeks old, okay okay maybe a couple of months. The oil I had on hand was un-opened quicksilver two stroke oil but that was about 2 years old. So I had a fresh mix of old oil and oldish unleaded. Could that be the problem? It's clearly not preventing combustion altogether as it runs briefly so I was wondering if I could discount the fuel freshness and need to worry about air leaks or head gaskets or fuel starvation or crankcases...what are the symptoms of duff petrol anyway?

Thoughts gentlemen?

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Oyster 49
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Re: GFP 40+ starts but won't get going

Postby Oyster 49 » Thu Jan 07, 2016 6:58 pm

Welcome to the forum, and a perfect find at that price.

It sounds like the engine needs a detailed service, checking everything. I would tackle the following list:
1. Remove the head and clean out the waterways, check the water jacket for cracks and fit a new head gasket.
2. Remove the tank and clean out using paraffin then a solution of caustic soda.
3. Remove and clean out the fuel line, it will most likely have sludge in it from old dried out two stroke mix.
4. Clean and gap the points, replace the HT lead and spark plug.
5. Drain and replace the gear oil.
6. Clean and oil the throttle lever and cable.
7. Strip and clean the carb, make sure all jets are clean and correct needle is installed.

After that try it out again with fresh fuel, and see how it goes.

Ps we like pictures here :P
Last edited by Oyster 49 on Thu Jan 07, 2016 10:36 pm, edited 1 time in total.

headdownarseup
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Re: GFP 40+ starts but won't get going

Postby headdownarseup » Thu Jan 07, 2016 8:20 pm

I couldn't have put it any better Adrian.

Yes, clean EVERYTHING. Dont be afraid to get the head off too as this can hide a multitude of woes that goes un-noticed till it's too late
The motor has probably been stood around since god knows when, so i'm fairly confident with some extensive cleaning it will run nicely.

I've often used fuel that was last used over 6 months previously and still got my motors to run. (just for testing purposes only you understand)


Jon

Shamba
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Location: South Devon

Re: GFP 40+ starts but won't get going

Postby Shamba » Thu Jan 07, 2016 9:05 pm

Well it seems that's my weekend spoken for :P

I don't have a blow torch but I do have a hot air gun which has proved quite useful in the past for freeing seized studs and will hopefully be upto the job.

I'll be sure to send pictures as I uncover whatever it is I find.

Cheers guys

Shamba
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Re: GFP 40+ starts but won't get going

Postby Shamba » Thu Jan 14, 2016 4:25 pm

As promised some pictures; here she is head and tank removed.

IMG_2233.JPG

IMG_2231.JPG


Note the new stainless clamps and "hook" from SOS.

I got round to removing the head this lunchtime having sprayed everything in penetrating oil for a couple of evenings. Came apart easy with no heat required.

IMG_2226.JPG


To my un-tutored eye the head looks okay. No carbon at all. The bore looks clean also with no obvious scores.

IMG_2229.JPG


The water jacket looks pretty solid with rusty gunk so well worth getting the head of and having a poke around in there.

I also noticed for the first time (unless i broke it when I broke the transom screws) that the drive spring is broke...so another item on the shopping list.
IMG_2225.JPG


More to follow....

ps not sure why the pictures have become rotated but I'll try to keep things on an even keel in future.
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Shamba
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Location: South Devon

Re: GFP 40+ starts but won't get going

Postby Shamba » Thu Jan 14, 2016 4:29 pm

As I whipped the head off without checking compression what do you think wrt rings? Having got this far should I remove the barrel as well and change the rings as a matter of course? Can you check wear using a feeler at the gap between the ends? Or am I best leaving well alone....

Any recommendations?

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Oyster 49
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Re: GFP 40+ starts but won't get going

Postby Oyster 49 » Thu Jan 14, 2016 6:39 pm

Good work so far. As you are that far down it will only take a few minutes to replace the rings, and not much cost. Well worth it I think.
Whilst the head is off give it a good clean up and also check the gasket faces for flatness. The easiest way to do that is to get a large sheet of wet and dry medium grit perhaps 400 grade, then wet the wet and dry and put it on a flat work top, run the head around on the gasket face and see where the high spots are. Keep going until it is flat, and do the same on the cylinder face, then fit a new gasket.

Give the water jacket a really good clean out too a long thin screwdriver works well for this.

Assemble it all back and you are good to go.

Don't forget to make sure the fuel system is spotless, including the fuel pipe. The tank can be cleaned out by filling with paraffin and leaving overnight, repeat and finally soak for a few hours with a caustic solution. Always add caustic soda crystals to water not the other way around. Another good way is to put a couple of dishwasher tablets in the tan and fill with hot water.

Do all this and see how it runs. You did buy a new plug and HT lead too?

Shamba
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Joined: Wed Dec 30, 2015 6:40 pm
Location: South Devon

Re: GFP 40+ starts but won't get going

Postby Shamba » Thu Jan 14, 2016 6:57 pm

I was quite please with how its come apart so far. Fingers crossed that this does not means that gremlins are waiting to strike.

Good suggestion re the rings I'll add them to my shopping list.

The new plug is in (you can see its shiny electrode poking through the head picture) and I have purchased but not fitted some HT lead and a new plug cap.

The existing plug cap is a hard plastic job with a hole through which the spark plug terminal thread sticks, secured by a nut on the outside. In fact the old cap seems superfluous as the HT lead has a crimped fitting that is introduced into the cap and effectively screwed to the top of the plug (through aforementioned hole in the cap). The sole function of the old cap is as a splash guard so far as I can see.

The new plug cap is one of those close fitting rubbery jobs with a thing like a woodscrew in the centre to screw into the HT lead and a screw clamp to secure it tight to the HT lead.

The HT lead I purchased was good quality HT lead with a multi-wire centre conductor. I have not yet looked at how I can fit this to the magneto end...will this be a problem? Do I need to crimp a fitting on?

I like the dishwasher tablet tip. I've no caustic soda on hand but dishwasher tablets will be no problem to swipe from the kitchen.

Thanks

Steve

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Oyster 49
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Re: GFP 40+ starts but won't get going

Postby Oyster 49 » Thu Jan 14, 2016 7:47 pm

That old plug cap you have is a quite desirable Bakelite one. Don't throw it away as we all like those. The HT lead is held at the mag end into the fitting by a small screw. Take the fitting off and you will see how it works.

headdownarseup
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Re: GFP 40+ starts but won't get going

Postby headdownarseup » Thu Jan 14, 2016 8:45 pm

Absolutely we adore bakelite.
Keep the old plug cap as you never know when you might be restoring something back to original condition/spec.


Jon

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John@sos
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Re: GFP 40+ starts but won't get going

Postby John@sos » Thu Jan 14, 2016 10:40 pm

Keep at it Steve, you are nearly there, more spares on the way shortly!
John
SOS

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Charles uk
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Re: GFP 40+ starts but won't get going

Postby Charles uk » Thu Jan 14, 2016 11:01 pm

Your symptoms do rather sound like a blockage of some sort in the main jet area.
Make it idiot proof and someone will make a better idiot.

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John@sos
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Re: GFP 40+ starts but won't get going

Postby John@sos » Thu Jan 14, 2016 11:29 pm

Hi Steve

try using fresh fuel mix when you have cleared that block out and replaced the head. Do not forget to use RTV sealant, it is the only one I recomend. (And Seagull recommended!)

I have been caught out myself with stale fuel and the symptoms are just as you describe, 10 to 15 seconds and peters out, flood and try again, just repeats. you are doing all the right things.

I would not replace rings unless they are broken or signs of any rust on them. 100psi when new, runs OK at 85psi. you need a proper compression tester and full throttle, no choke and 3 pulls to get a good reading. Rings rarely wear out. New ones will take a time to bed in and compression will be lower until they do. If you need them just £11.50 a set.

note Bing carb and it still has the intake cover! tie it on, if they vibrate loose, they sink! No spares of them available...

Hope the workshop warm, freezing here!

Regards,
John
SOS

Shamba
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Joined: Wed Dec 30, 2015 6:40 pm
Location: South Devon

Re: GFP 40+ starts but won't get going

Postby Shamba » Fri Jan 15, 2016 1:07 am

Thanks for the tips. The main problem with my garage / workshop is overcrowding, although it is now blinking cold also.
image.jpg


This weekend I'm preparing an old Series Landrover for an MOT so seagull fettling will be limited to scooping out what muck I can from the waterways and cleaning (tanks, fuel hose, carb, points and anything else I can). I also have a little Yamaha 2b to rebuild and once they're both up and running (must stay positive) I aim to do some comparison trials in a couple of little 8' plastic boats I have.

First things first though. I'll post pics if I dig anything interesting out of the engine!

Cheers

Steve
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Shamba
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Location: South Devon

Re: GFP 40+ starts but won't get going

Postby Shamba » Fri Jan 15, 2016 1:15 am

I did take the jet out to clean it with carb cleaner spray Charles and wonder if I did more harm than good. I also took the float bowl off and squirted cleaner up through the jet (throttle slide removed) with the carb in situ and it shot through. I wondered about an air leak as I was getting some backfires but I guess fuel starvation would also weaken the mixture....

For now the clean everything and reassemble is the way to go. Maybe I'll be lucky enough to find an identifiable cause (eg sludge in the fuel pipe) but I know your not always that lucky :P :P

We shall see

Steve


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