Problem at full throttle

[ddevore]

Hey Guys, I'm having a problem with my boat and am curious if anyone has any pointers.

Starting yesterday when I launched I idled around for 3-5 mins waiting on the wife, when all was set and I nailed it up river all was good for a few seconds then the damn thing fell on it's face... I dropped the throttle and kept it at around 3000 and everything sounded good. Nailed it again and the same thing happened. I kept ran for maybe a minute then hit it and it was golden.

Same thing today... Any suggestions on what to do to take care of this? It's a 2000 Marine Power 454 that's running carbed. I'm guessing the qudracrap carb is the main issue.

Thanks for any info guys - dead boats on the strip are a bitch!

Dennis

 

[River Cowboy]

would check the secondairys sounds like they are stuck down
second in carb filter cloged
or fule pump

 

[bigriver48]

Fuel tank anti siphon valves sticking??

 

[Jetmugg]

Some Q-jets use a sintered metal filter on the inlet. They clog very easily.

Sounds like it could be a fuel supply problem.

 

[ddevore]

Thanks for the info guys, I'll check both out.

 

[ddevore]

Would the spark arestor deal on top of the carb being covered in crap cause this? Come to think of it it may be just the right tank so I'll mess with it. Thanks again guys

 

[Cajun]

Run a fuel pressure gauge and eliminate that doubt.

 

[jetboatperformance]

Definately sounds like a classic "fuel starvation" issue ,like said here check downline filters , check for spongey lines etc call if you need help Tom

 

[ddevore]

Hey Tom, thanks for the reply (Cajun too). I moved the fuel pump to the transom because it would vapor lock all the time in the heat, now if I run the fan it is fine (or was). I did replace the fuel pump a year or two ago to get rid of the problem and stuck a gauge on it, it's around 3-5 PSI all the time - is that enough?

Tom - I did pick up a steering cable from you a year or two ago and with your advice on the routing I'm stoked on how it works. I may need a throttle cable and I know where I'll buy it!

 

[parkerpowersports]

5-7PSI ON CARB ENGINES

 

[jetboatperformance]

Hey Tom, thanks for the reply (Cajun too). I moved the fuel pump to the transom because it would vapor lock all the time in the heat, now if I run the fan it is fine (or was). I did replace the fuel pump a year or two ago to get rid of the problem and stuck a gauge on it, it's around 3-5 PSI all the time - is that enough?

Tom - I did pick up a steering cable from you a year or two ago and with your advice on the routing I'm stoked on how it works. I may need a throttle cable and I know where I'll buy it!

Sounds like your closing in on the problem however as said the FP is low What pump ? and where in proximity to the level of the tanks is it ? Tom

 

[ddevore]

Nice, I'd love to get this thing right... Being dead on the river SUX. The pump is the factory pump that comes on a marine power 454. I replaced it once thinking it would help, it looks like a small carter of some sort. I may have the old one in the garage, I'll see if I can find it.

The pump is on the transom, I'd guess it's about 3/4 the way to the top of the tanks, but it may be a little lower.

Would a higher pressure pump help out, or could I just have it installed in a crap location? It was originally on the motor near the distributor but it kept vapor locking pretty bad. I figured a cooler location would help out, and it did some (this was 5+ years ago).

 

[randyjet]

Another thing a lot of people don't know is most the braided line and most rubber line won't last with the additives at the pump. I was running Earls line and had a similar problem and couldn't get it to maintain pressure. The braided line had pin holes in it. It was slowly being dissolved by the alcohol and eventually failed. I called Earls because I used the same line on my airplane and didn't want the same issue. They told me av gas has no alcohol and would not react like pump gas. They suggested Teflon line if you run pump gas they said the worst is letting it sit in the lines like in a boat.

 

[Flyinbowtie]

Devore 3-5 PSI is not enough, should be 7. that pump, IMHO, should be as low as possible in comparison to the tanks.
If this is something new I'd look at the pressure issue, and it does sound exactly like that fuel filter in the fuel inlet area of the carb is plugged. They are very fine filters, and if it was mine I'd change that, and carry a spare.
That is where I would start.