What's wrong with my 4.3L TKS????

[Camaro4life18]

I've posted a couple times with some issues I was tracking down, but seems like none of them are at the root of my problem. So I'm going to post the whole story.

I have a 2005 Ebbtide with a 4.3L TKS.
Symptoms...
Starting for the first time is no problem. Starts with a couple cranks and runs great while the TKS is open. After some time the TKS warms up and closes, and it runs fine for a couple minutes. Then while running at 3000 RPMs, they will drop and the engine almost stalls. It will idle fine after this for another minute or two, then will start stalling at idle. Restarting requires some pumping of the throttle. Carb cleaner down the barrels, or in the float tank will keep it running and raise RPMs until it burns out. Loud popping noises under the hood when it tries to run at high RPMs.

What I have done...
Initially started tracking down electrical problems, found a bad diode in the TKS circuit that was sending 8v of battery power to the fuel pump... As long as the battery had power, so did the fuel pump but you could never hear it running. Replaced the diode and the fuel pump, with the $300 factory pump. Checked the distributor and found cracks, replaced it and the rotator.
After that I started it on muffs and still had the same problem. Ran it up to 3000 RPMs and started looking for fuel leaks and found the gas tank hose was loose on the filter. Tightened up both ends. Oh, and I did replace the fuel/water separator. After tightening up the line it ran fine on the muffs...of course when I got the family out on the lake we got a half mile into a tube ride with my boys before it quit and I babied it back to the ramp.

At this point I pulled the carb when I got home. Some small sediment in the float tank, but the Jets look clean. Someone has done some work to it, because the Jets are stripped. I'm going to rebuild the carb and set everything to spec from the manual I found, but I feel like I'm just fixing things to be fixing things. I'm open to any ideas or suggestions.

Oh, I did try running without thegas cap on, vent line has no problems.

 

[achris]

Find yourself an outboard remote 20 litre tank. Hook that up and see how it goes. If the problems remain, it's 'engine' side. If they go, it's tank/line side.

Have you checked the engine mounted filter? look at the housing for cracks where the fittings screw in..

Chris......

 

[Bt Doctur]

the TKS is a POS, replace it with the Rochester

 

[Camaro4life18]

Find yourself an outboard remote 20 litre tank. Hook that up and see how it goes. If the problems remain, it's 'engine' side. If they go, it's tank/line side.

Have you checked the engine mounted filter? look at the housing for cracks where the fittings screw in..

Chris......

Well, I checked around the fittings, didn't see any cracking, but the fitting itself was loose. Could be my whole problem. I'll have to try again once I get the carb rebuilt.

 

[achris]

Loose fittings are usually an indication of a cracked housing. The fitting it tightened up (usually too tight :facepalm, the housing cracks, and that makes it FEEL like it's loose.

Pull the housing off and examine it very closely. Put a fitting in and start tightening it up, you may see a crack open up.

Chris......

 

[Camaro4life18]

Well, I check the fuel water separator housing and didn't find any cracks, but I did find 4 fittings on the suction side of the pump when only 2 are needed. Plus one is the multi Barb style fitting which I personally don't like. I replaced the hose fitting with the sing Barb style that works betterwith a hose clamp. And I doped it all up with HP permatex.

I also noticed the hose to the tank looks rather aged, possible the original. So I decided to take it off to get a replacement, and I discovered the anti-siphon valve was all corroded around the hose. Like a bunch of dust came off when I pulled the hose off.

So my question now is, is the anti siphon valve truely needed? I've read about others having similar issues as I and it traced back to these valves. My method of thinking is the needle in the float bowl of the carb should stop siphoning, correct?

Either way I'm impatiently waiting for my carburetor to be rebuilt.

 

[achris]

The anti-syphon valve is not for the engine, it's in case the fuel line is damaged and free to 'free flow' from the tank into the bilge.

 

[Camaro4life18]

Update: Ran a whole half tank of gas on the lake with no issues! Kids got to tube, I got up on skis, the wife was pleased!!!

What I found and fixed to resolve my issue...
I believe the root cause was actually the carburetor running too rich. This was seen with the drops of gas dripping from the venturi's into the carb barrels. I shipped the carb off and got it rebuilt, took a long time, hence the delay in the post. Once I got that on, I took it back out on the lake where it ran better, but eventually had the same problem....although it would idle like a champ this time around.
Next I pulled all the spark plugs and discovered a lot of black soot around the points. Basically it ran too long with too rich of a mix and fouled the plugs. Replaced all the plugs and took it back out, and everything ran great. I still don't think the TKS module is working 100% right, and at this point I wish I didn't rebuilt the carb and just replaced it with the Rochester or the Holley EFI. I already dumped money into the TKS carb, so I wanna make it work at this point. I think the TKS module needs replaced as well as another Diode. I think the one I got new is bad.

There are other things I have done as well that probably helped the situation, but I think it all goes back to the carb running rich and eventually fouling the plugs. Here is what else I replaced:
1) Fuel pump
2) Fuel hose to tank
3) Anti-siphon valve
4) TKS Diode

Thanks to everyone for suggesting things for me to look at.

 

[kwortman]

There are other things I have done as well that probably helped the situation, but I think it all goes back to the carb running rich and eventually fouling the plugs. Here is what else I replaced:
1) Fuel pump

So I've been wondering about my fuel pump for a while and actually have a new one but its located down by the fuel separator filter and I'm not completely sure how to get it out (or back in for that matter). Would you mind sharing how you got your pump out if it located in the same location. I have a 2007/2008 alpha one 4.3L TKS with similar issues. For me to get a wrench down to remove the fuel filter looks like it might require taking off the crankshaft pulley which I am not thrilled about. Hoping you might have an alternate solution.