300x boggs on hole shot

[gofastallison]

back again; 300x boggs out of the hole; seems like over propped but been running 25 pitch for 5 years plus; was having problem with fouling of plugs but that problem corrected by Don after cleaning and calibration of injectors; that is plugs are now burning clean ; engine seems to hesitate then correct itself and out of hole like it should; a few times seems to be missing when running? it was 24 degrees this Saturday and it was slow to start;

[ddantidwell]

check the screen in the high pressure that sits on top of the vst.

[EuropeanAM]

James:

You might also want to look at the MAP Sensor.

Oil buildup in the hose... faulty sensor, or oil buildup IN the sensor have all been known to cause such problems.

Perhaps the "simplest" method is to locate a "known good sensor" to install for testing (with a known-clean hose)... if hose equipped, of course.

It's a "Speed-Density" injection system.... the Map sensor is the "Density" side of the equation. Without accurate Density information... a wide array of "wierd" problems occur.

[Nikon Man]

Don't mean to highjack, but I've gotta ask........what pray tell are you running a 25P prop on with a 300x ?????????

[gofastallison]

My boat is a Allison XB21 Prosport with a sportmaster case with a 1:62 ratio and it seems to work best for fishing however i will run if called out; just had prop modified to ally cut at Soddy Daisy Tenn. I also have a hoss cut chopper for speed but blows out; out of the hole. Fishing i do a lot of short jumps which does not help my problem. I appreciate and will take any input from folks with more experience than myself. Don was a big help when my plugs were fouling out due to bad injectors. Counting on you guys to get me going again; thanks

[gofastallison]

My sensor in intake without hose; what sensor should i look to borrow; don't have any buddies with 300x but some with various motors such as 250 pro xs?

[Nikon Man]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by gofastallison &raquo;</td></tr><tr><td class="quote">My boat is a Allison XB21 Prosport with a sportmaster case with a 1:62 ratio and it seems to work best for fishing however i will run if called out; just had prop modified to ally cut at Soddy Daisy Tenn. I also have a hoss cut chopper for speed but blows out; out of the hole. Fishing i do a lot of short jumps which does not help my problem. I appreciate and will take any input from folks with more experience than myself. Don was a big help when my plugs were fouling out due to bad injectors. Counting on you guys to get me going again; thanks </td></tr></table>

After reading what boat you have, prop bog is definately not the problem w/a 25P.......Follow Don's advise to the letter, he will get you running again.

[Todd D]

You said you had the prop modified.... have you tried anything else since your problem. the prop may be cup locked........

[gofastallison]

No; have never heard of cup lock; not running any plugs in prop so exhaust will blow water away so i can get RPM's up; Please tell me about cup lock;

[Largemouthlou]

Some times on a modified ear the prop man will add extra cup along the whole edge (trailing and tip) to compansate for cutting the blade, and this tends to really tighen up a prop, Some times an over adjustment by the thickness of a pc of paper is all it take.

Have you ever checked the mid section exhaust holes to see if they got plugged up by carbon seeing as how your injectors were previously out of whack?

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by gofastallison &raquo;</td></tr><tr><td class="quote">My sensor in intake without hose; what sensor should i look to borrow; don't have any buddies with 300x but some with various motors such as 250 pro xs?</td></tr></table>

The BEST way to check this MAP sensor is via use of the Computer Diagnostic System (however, even this is not foolproof... it requires extensive knowledge of what the readings "should" be under various conditions).

You could borrow one from a donor 225/250 ProXS or XS, for instance (just for testing).

Regarding Lou's comments on exhaust, that's a REAL possibility. See the following post for more information on that topic:

http://www.bbcboards.net/zerothread?id=637339

[gofastallison]

Next trip I will take another prop; no did not look for plugged tuner but I will; also going to look for a map sensor. How much does sensor cost?

[EuropeanAM]

You've got an IM.

[gofastallison]

Thanks to everyone that give me input; good news is that I ran boat yesterday and boat is screaming again; checked everthing and the main problem was the gas line from the tanks to engine; liner was loose getting in check valves on primer bulb. This web site ,Don Weed , and you guys are the best; thanks again.

[gofastallison]

opps; spoke too soon; after several trips with all okay it finally happen again; fouled #4 plug again; changed out and running good now but based on history with my 300x it will happen again?

[EuropeanAM]

James:

Did you rebuild your PULSE FUEL PUMP at the same time you replaced your fuel lines and primer bulb? How about the FUEL FILTER?

It's critical that ALL items are addressed at the SAME TIME. The same debris that would have been in the primer bulb would also have been passing through the pulse fuel pump, into the fuel filter, and in worst-case scenarios, can even pass smaller particulates through the VST into the fuel rail, injector filters, and the injectors.

Additionally, if you have a pinhole or perforation in one of the fuel pump diaphrams... it will result in excess fuel being dumped into the "driving" cylinder (the cylinder producing the pulse for that diaphram).

Reeds inspected?

[gofastallison]

Don; replaced fuel line after rebuilding of pump; as discussed I did replace #four plug and ran the next day in tournment; did fine; removed plug and it is burning cleaning; maybe a bad plug? Guess I will find out? Thanks

[EuropeanAM]

Glad that seems to have you up and running again... might want to monitor that particular plug after every couple of trips to the water.

Excessive amounts of idle time can contribute, of course (other than necessary warmup time)... but it sure does sound like you simply had a bad spark plug.