AQ231A Dieing under load

[LegacyT]

Hi all.

My Motor is dying after getting warm when run above 3000 rpm. It starts and idles great. The problem seems to be getting worse in the last couple days. It'll just die completely unless you throttle back. I'd like to check the fuel pressure but that means cutting up the stock steel fuel lines... I'm wondering if the mechanical fuel pump is acting up. I replaced the main fuel filter and the checked the carb filter. I found a couple little chucks of rubber in the carb fillter wondering if those are parts of the diaphragm. Also is fuel supposed to flow up the clear tube that is connected to the pump and flame arrestor?

 

[captmello]

Re: AQ231A Dieing under load

No, fuel should not be in the clear tube. If there is, you need a new pump.

 

[LegacyT]

Re: AQ231A Dieing under load

Well replaced the fuel pump. Old one was crap. But the motor still does the same thing. starts and runs decently till about 2500 rpm. With more thottle it'll some times rev up for abit then die or not rev up at all. would a weak battery do this? also wondering if the coil or ballast resistor are shot. I have new cap n rotor, Points are set correctly with dwell in spec. It had new plugs and wires last august. Any thoughts?...

 

[jerryjerry05]

Re: AQ231A Dieing under load

The voltage at the + side should be 9 while running.
Is the coil hot,too hot to handle? You should be able to touch it and not have to pull away.
Quadrajet carb. Look at the filter in the carb.
A good fuel pump tester will have the fittings in it so you don't have to break/cut any hard lines.
A weak battery wouldn't start the motor.
Also check the tank pickup for blockage and the vent hose for blockage.

 

[captmello]

Re: AQ231A Dieing under load

If it were me, I'd go through and check the timing, dwell etc to make sure they are still correct. Also make sure the timing is advancing. Easy enough to check, along withe the suggestions Jerry made.

 

[LegacyT]

Re: AQ231A Dieing under load

Checked the timing, dwell etc. everything was good tested the ballast resistor its slightly higher than specs at 1.2 ohms over recommended .5-.6. Also the resistance on the primary side of the coil was at 2.1 ohms over the recommended 1.6-1.8. could these cause all those issues? Also checked the vent its fine it gurgles when you fill the tank. I noticed on the pickup out of the tank there is a barbed nipple for the rubber fuel hose. Inside it had a spring and and a ball bearing that gets sucked back with vacuum. do these ever cause problems?

 

[captmello]

Re: AQ231A Dieing under load

You are describing the antisiphon valve at the fuel tank. Yes, they have been known to stick...

If its not too much of a hassle, you could try going out and seeing if pouring fuel in the carb when it starts to die helps. If so, you clearly would have a fuel issue.

Also,if you pull the fuel line off the carb and stick the end in a safe container, and turn over the motor without starting (pull the coil wire), it should pump a pint of fuel in 15 sec+/-.

Sorry, I know these are not scientific tests...

 

[LegacyT]

Re: AQ231A Dieing under load

Well ran the motor and tested the timing. It was ok good for abit. Then the timing sticker on the balancer would vanish and end up at 7 o'clock on the balancer. Then it would come back n be ok then disappear again. Does that mean the distributor is shot?

 

[LegacyT]

Re: AQ231A Dieing under load

Kept checking the timing while running on plane seems to be holding... It's weird it has plenty of punch to get up on plane with full throttle and then accelerate but then starts to bog 2500-2700 rpm

 

[captmello]

Re: AQ231A Dieing under load

Well ran the motor and tested the timing. It was ok good for abit. Then the timing sticker on the balancer would vanish and end up at 7 o'clock on the balancer. Then it would come back n be ok then disappear again. Does that mean the distributor is shot?

Interesting...I don't know the total advance for your motor off the top of my head, but it should be advancing to around 30 btdc as the rpms get up toward 3000+ rpm. Check your manual for specs. It sounds like its advancing 180 deg! wth.

Whst does the engine do when the timing appears to change so dramatically? It couldn't possibly continue to run the same.

Did you try testing for a fuel shortage?

When the motor is bogging, does it backfire at all?

 

[LegacyT]

Re: AQ231A Dieing under load

Yeah it was weird. The motor continued to run fine in neutal when it did it it... It's a cheap timing light maybe that's it... I know the manual calls for 14* advance at 2500 past that I'm not sure. But it is advancing... I ran the boat from a Jerry can with the tank line in it. Still does it... Found the wire from the coil to the distributer had 200 ohms resistance replaced that. Still does it... Have a new condeser coil n ballast resister on the way gonna try that n go from there...