350 feels like I am letting off the throttle and back on again

[Karl.]

Hi it's me again, after having the boat running for some time without any problems I am having some issues again.

When towing a ring the boat goes great, it's only after that and I go to pull a skier I am having problems. It's nearly like the boat is getting starved of fuel. Once I give it a small bit of throttle in gear it would die out instantly. Or if I take it out of gear and rev it it stops at about 3500rpm.

I have to let it idle for a while to get fuel back to it.

I have pulled the fuel filter and replaced it with a new one.

The last time I was having problems with dirt in the lines and tank so I have cleaned it out, changed the filter and now after about 5 hours I have changed the filter again. I haven't tested the new filter yet to see if that helps but the old one was full of fuel and even had some dirt and water in it so I'm hoping this cures my problems.

Also after the old filter sat for 30 mins the seal seems to have expanded

Note, the seal was fine once the filter came off so I don't think that would have caused me any problems.

Here are some pictures of my spark plugs after fitting my new carb.

What's everyone's opinions on these?

Thanks

 

[Lancer76]

Have you replaced the little 2" long fuel filter in the carb housing? If not, that may be restricting fuel flow to the carb bowl.

 

[Karl.]

Hi, the new carb came with a new one and after running for a while and finding out I have dirt in the tank I replaced this with a really fine white mesh one. I will take that out and give it a clean.

Would it be possible that the pipe going into the tank is split and it's picking up air or even lying to one side and starving itself?

Is there replacement pickup pipe available?

 

[Scott Danforth]

just pull the anti-siphon valve and look at the pickup tube. they are replaceable. just need to know length.

 

[alldodge]

What filter number is that?

 

[Karl.]

https://m.ebay.co.uk/itm/Fuel-Filte...1690443614?_mwBanner=1&_rdt=1&epid=1264605121

These are the filters I am running

Originally the filter was 35-802893T

 

[alldodge]

Thanks, was wondering if there was an issue which could be found with the rubber gasket, I did not see any. The gasket reminds me of rubber which is not compatible with gas/ethanol

 

[Karl.]

I am also going to be changing the oil in my 71c velvet drive. It's never been changed that i know of but the drive does seem to be in good condition.

I have sucked the existing oil out of the bottom of the box bit never got to suck it out of the cooler etc.

The current oil is a green colour.

I am going to replace it with Dextron oil. Will it be ok to mix the small bit in the cooler with the new dexron oil for 1/2 hours and then suck it out again and fill with dexron oil to give it a proper flush.

Thanks

 

[alldodge]

Don't see an issue. manual says Dexron, Type F or any hydraulic fluid which meets C-3 oil specifications. Does mention not to mix different oils, but what your doing would not give me concern

 

[Karl.]

So I got the boat in the water this evening, let it idle to it went up to temperature. (I just fitted a thermostat after 10 years of not having one so a lot of watching the gauges etc before I moved)

Turned it off and let it settle and checked the oil and got it topped up as it was still cold.

Got that going and took off and the boat was going great, took it for a few fast runs watching the thermostat to make sure everything was ok and it went great thankfully.

Came back and drained the new oil (it was a brown sort of colour from mixing the green and red oil) and refilled it with fresh dexron 3 oil and went for another few runs and it went great. Temperature hand just moving slightly between quarter and half depending on load etc.


Tied it up and let it idle while I put the trailer in the water and as soon as I got back into the boat it died out. It was idling for about 3/4 mins. Again I had someone keep an eye on all the gauges and everything was perfect.

I tried starting it and it turned and turned over. When I got it started I was able to rev the engine fine and even let it idle but as soon as I put it into gear it died out again.

It was getting dark and I was floating down the river with no one else on the river and failed attempts to through a rope to my girlfriend.

So I grabbed a spanner and give myself a slight advance of the ignition timing and it fired up straight away and I was able to get back to the trailer.

When checking the ignition timing before I fitted the thermostat I was at about 15/16 btdc at 6/700 rpm. (This also happened before I fitted the thermostat the last time I was out so I'm not sure if it's related)

Any ideas? Sorry for the long boring post

 

[Karl.]

I also noticed that the headers are nearly next to cold now after fitting the thermostat. Is this normal?
​​​​​​

 

[alldodge]

Where at 15 to 16 BTDC and you had to advance it more to keep it running to get on the trailer. That being the case, I would start looking into fuel issue first.

I also noticed that the headers are nearly next to cold now after fitting the thermostat. Is this normal?

I don't see a problem, your moving a lot of water now, and most is going thru the exhaust instead of part block and part exhaust. If you were over heating I would look more in depth

 

[Karl.]

Ok, is it worth while fitting one of the hand primers?

I have cleaned out the tank, all new lines, a couple of new fuel filters, new carb.

There can't be much left to do with the fuel system.

I made sure to the hose down into the tank was sealed and there wasn't much chance of air getting sucked in.

I will replace the hose going into the tank and go from there.

 

[alldodge]

You might be getting to much fuel, or maybe the fuel pressure is low.

Hand primers for testing should not pose an issue

All gas motors work the same way, they need fuel, air and spark in the correct amount

 

[Karl.]

Ok, I could have a look at the idle air screw's on the quadrajet just to make sure that they aren't getting fouled at idle.

Thanks for the tips