Modded 225EFI users please step in...I cannot run a 250 fuel box.

[Gamblinman]

Here are my mods on a 2000 225EFI: Lightweight flywheel, 300 PM heads, TDR reeds, 300 PM ignition box and cowling mod. Motor has 4 butterfly intake. Compression is 125 lbs. with 4 to 6% leakdown, so the powerhead is strong for a 17 year old motor.
I have tried every 250 fuel box (EFI and XB) and 300 fuel box that I can get my hands on and cannot get the motor to turn over 4200 RPM's with a fuel box other than the original. I have a set of Simon modified boxes and still have the same issue
I can put the 225 EFI fuel box on and it will go to the 5800 limiter. Plugs have great color and piston tops look excellent with the 225 fuel box. TPS in spec, all other sensors check OK. I've replaced all the coils one at a time to see if it might be something there to no avail. I usually run Iridium plugs, but bought a set of Champions just to eliminate that being an issue. 0T161696.

Has anyone else run into this? Any ideas? Welcome to any suggestions.

Thanks,

Gman

[Collin C.]

I have no answer but, I would call simon and pick his brain. I have alll mods you have, I have had no issues in 5 years. Simmon did my boxes for me then and they have worked perfectly.

[EuropeanAM]

Use ONLY QL77CC Spark Plugs.

What is your FUEL PRESSURE:

-At idle
-Under Acceleration
-15/30/60 seconds after shutdown?

[Gamblinman]

Use ONLY QL77CC Spark Plugs.

What is your FUEL PRESSURE:

-At idle
-Under Acceleration
-15/30/60 seconds after shutdown?

I have the Champions in it now, just to eliminate that possibility. I've run the Iridiums for years with the 300 PM ignition box and 225 EFI fuel box with no issues. Fuel pressure sets at 34 lbs. at idle, during acceleration, I see a drop to 32, then it comes right back to 34. Still have over 30 lbs after 60 seconds.After 5 minutes, it's bled down to 20 lbs.

[Gamblinman]

I have no answer but, I would call simon and pick his brain. I have alll mods you have, I have had no issues in 5 years. Simmon did my boxes for me then and they have worked perfectly.

I've talked to Simon and he has no ideas. I have a set of his boxes and same scenario...motor just flattens out at 4200 and won't rev any higher.

[Gambler69]

Hey Gamblinman! I had the same problem when I modded my Gambler Intimidator with a 2001 225hp efi. Everything worked fine but the computers! I could only get around 4500 rpms. I tried everything. Had Simon double check the flash...etc.. I just went back to the stock computer's. The mods gave me really good low end and mid range! Didn't see any top end gains though.

[Gamblinman]

Hey Gamblinman! I had the same problem when I modded my Gambler Intimidator with a 2001 225hp efi. Everything worked fine but the computers! I could only get around 4500 rpms. I tried everything. Had Simon double check the flash...etc.. I just went back to the stock computer's. The mods gave me really good low end and mid range! Didn't see any top end gains though.

Sorry for your issue, but its good to know I'm not alone.

I've sent killer bee a PM...maybe he can respond on anything he think it may be.

[Gambler69]

Try switching out the flashed ecu's with the stock ones. Do the fuel and later switch the ign one and see if you can find the problem. I think my issue was a bad ecu. I kept my stock ones.

[Gamblinman]

I've switched boxes every which way and tried different combinations ...it always starts when I use a different fuel ecu other than an stock 225 ecu.

[Gambler69]

Check the grounding on that ecu. But I think that you may have a bad fuel Ecu. The best gains from your mods will be from the 300hp heads. The flywheel will help a little but not much. I'm going to pm you with my number if I can help.

[EuropeanAM]

Injectors been validated, cleaned, calibrated and serviced?

A fat or flooding set of injectors would cause what you're describing.... especially if combined with a light hull.

[Gamblinman]

Injectors been validated, cleaned, calibrated and serviced?

A fat or flooding set of injectors would cause what you're describing.... especially if combined with a light hull.

Injectors were cleaned/serviced last spring. I did receive a report on their condition, but not near as technically detailed as yours. No injectors were replaced.

Injector report.jpg

[Gamblinman]

Check the grounding on that ecu. But I think that you may have a bad fuel Ecu. The best gains from your mods will be from the 300hp heads. The flywheel will help a little but not much. I'm going to pm you with my number if I can help.

I appreciate the offer of assistance. I already have 300PM heads on the motor. I've tried the gamut of 250 and 300 fuel ECU's...even known good ones from friends engines..same outcome. I've replaced the ground just to make sure. Even the matched set of Simon boxes perform the same way.

I find it strange how well it runs with the stock 225 fuel ECU. If I hadn't done numerous plug and piston top checks, I would be concerned with a lean issue. I use good, high test fuel and Quikleen with every tank.

[Gambler69]

I was thinking that maybe the 250xb fuel curve was dumping too much fuel for my engine. After about a month of testing and ecu switching, I gave up on it and put the stock ecu's back on. The computers aren't going to give you any power gains anyway. The stock rev limit is good also. The 3.0 liters don't like to be ran over 6,000 rpm. Im thinking that your 300 promax heads are cut to 65cc. If you had 300x heads, which are around 61cc, then I would say that the extra fuel may be needed.

[rvaha]

I have a similar setup with 250 fuel (not sure if its Xb) and 300 ignition. Compression about 110
on all 6. I don't have any issues. I do have dual pyro's that measure exhaust temp. Adding a set might tell you if it's going extra fat if you see the temp start to drop. Just another tool that might help. Good luck. I'll be watching for what you find!

[Gamblinman]

I have a similar setup with 250 fuel (not sure if its Xb) and 300 ignition. Compression about 110
on all 6. I don't have any issues. I do have dual pyro's that measure exhaust temp. Adding a set might tell you if it's going extra fat if you see the temp start to drop. Just another tool that might help. Good luck. I'll be watching for what you find!

Don't see many 3.0's with pyro's installed. That's an option.

[EuropeanAM]

Double check the data reported for the IAT (Computer Diagnostic System or DDT). Make sure it's not WAY, WAY off (have seen this a lot recently).

Sorry... report was only minimally helpful.

[Rich Z]

I believe between Don and I, we could poke about dozen holes in that flow test report. The injector flow test machines are worthless!