Evinrude Surging?

[SteveCan]

Hi Guys,

I have an old 70 HP Evinrude (I think Blaze has the same motor?) that has been giving excellent service.

A couple of weeks ago up at the pin, the fuel bulb got pinched and started letting air into the fuel - at high revs' it couldn't get enough fuel and started surging. We limped back at a lower rev setting and all was good.

We installed a new bulb and it seems to be working fine. However I noticed that we still had some surging at near WOT. Starting ans such is the same as ever - fine - but I am a bit concerned aobut the surging. I am nearly sure the the new bulb is airtight (it's certainly noyt leaking fuel) - could it be anything else?

Thanks for the help
Steve

[NQCairns]

Hi Steve, on the surface it does sound as if it is still leaning out near wot, you probably know that it is one of the surest ways to wreck a motor. I would go with your suggestion that it is still leaking, fuel will not leak out everytime with a pinhole or gap somewhere but a lot of air will displace the fuel at the motor under vacume.
I have a simple piece of clear plastic tube about 100mm long that I place inline, at one end the motor fuel connector plugs into and the other has a piece of copper tube inserted inside so that I can plumb into the main line. Any bubbles can be seen quite easily through this line.
While checking if the engine is still surging run it at the high revs needed for the shortest period possible time and also dont chop the throttle (this is when they go most often) to slow down, either ease it back or cut the ignition (most prefered) just in case. You could also just but a quality bulb and line to swap, and keep one or the other as a spare if it turns out not to be the problem. Have you emptied/cleaned the inline fuel filter? nq

[SteveCan]

Thanks NQ, that's good advice. I had already decided to get a service in the near future to have this checked out.

I did leave out one important little piece of information in my last post. :-[ Lately I have had some trouble with my sounder turning itself off for no apparrent reason. We thought that the wiring was the problem and replaced the connections at the same time we did the fuel bulb. Yesterday when heading out to the fishing grounds it was pre-dawn and although we did not have any surging, I noticed that from time to time the lights and electrics would drop out momentarily. Especially at low revs it was difficult to keep the sounder on as the power constantly fluctuated.

What is this 'electrical' problem, could it be responsible for the surging?

Sorry for leaving this out of yesterdays post...

Cheers
Steve.

[Big_Kev]

Sounds like a bad earth for the electrics problem Steve.
Check it all over, it can be as simple as a bit of corrosion on a battery terminal. a good rub with a wire brush.
Cheers Kev.

[NQCairns]

IMHO Kev is spot on. I noticed the same problem with my sounder last trip and the first place I will look is per Kevs advice.
If your motor is younger than near 74 you have an engine that makes all it's running needs as soon as it is started and the battery is just an electrical tank so most likely unrelated to your other problem but who knows for sure with boats, glad you are getting a service, let us know what they nut out. cheers nq

[SteveCan]

Thanks Guys,

I checked the battery terminals and the ground wire was gettnig a bit of corrosion around the join. I unbolted everything, lightly sanded the joints and put it all back together and sprayed with wd40.

The result - no more surging. :) Thank for that guys!

However the sounder still cut out again cruising around at low revs. I am going to investigate a few more options. I will still be getting that service done - you were on the Money NQ - it is a 74 model.

Thanks again for the advice - I hate to think what it might have cost me had I taken it to the shop first. :o

Cheers
Steve

[NQCairns]

Hi Steve, Glad you wirked it out, sounds like your engine is on the older side of the edge where they changed from a battery capacitor system to a self energising system.
Your motor needs a high amp hour fully charged battery with super clean and tight terminals at both ends of + & - at all times. The battery on yours is where the engine pulls it firing power when running. Running dirty terminals or a weak battery allows the very common habit of trashing the powerpack and fast. They hit you hard for a recon replacement too. Bloody sounders!!! hope you work it out.nq