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View Full Version : 300 pm wht am i burning so much gas?


PARKER RABE
11-01-2005, 08:36 AM
got a 300 pm on my mirage and god damn does it burn alot of gas , it has an svs on it but i put 10 gallons of gas in it and ran for 20 minutes??? on and off the throttle.....ive had alot of 2.5s , this thing is unbeliveable , ill burn double what a 2.5 will , should i try and lean it out , i dont have promamaters? dont want to burn it up< were going to the jungle run this weekend and ill have to bring extre fuel , just to cruz with everyone !!!! any help would be great , i have acess to a DDT :confused:
Fish
11-01-2005, 08:44 AM
not trying to keep up with me should help :D
1BadAction
11-01-2005, 09:32 AM
10 gallons of gas in it and ran for 20 minutes???:confused:

thats about right, 1 gallon per hour for every 10HP. has it been modded?
PARKER RABE
11-01-2005, 09:42 AM
rods heads and flywheel , little port work , but theres deffantly something wrong ! i got riding 20 minutes up the swannie and was at half tank ?????
1BadAction
11-01-2005, 09:44 AM
might be fat in the midrange, Laser inj is like that, but get a pyro on it before you go messin with anything... Big Ci, big HP=big gas bill.
NICE PAIR
11-01-2005, 10:01 AM
With the cowl off, facing the motor, at the tor right of the inj. plenum, there is a brass fuel transfer tube. I believe it has 2 hase's hooked to it. I had one on a 300 pm that broke the solder joint on the inside of the plenum, thereby spraying fuel uncontrollably into the intake. (flooded motor) Possibly a small crack or leak in this area could cause problem (over rich) you can probably look for leaks with the cover off, key on. DO NOT START ENGINE (run away motor with no air control) be careful of fuel & sparks.
jerry
11-01-2005, 10:09 AM
300s burn about 32 gal an hr. at full throttle..............
22VelocityProMax300
11-01-2005, 10:16 AM
Parker, I have a 300Promax on my Velocity and it is a mooch on gas.Stock,these motors get good fuel economy. I would do a plug reading,It should be brown and not black or worse yet blue black and wet looking.The 20 minutes you were running it were you flat out most of the time. I am able to get great fuel economy running a lot of time at 5000 rpms.Frank
PARKER RABE
11-01-2005, 10:17 AM
jerry this will burn 32 gal at 3000 rmp prob under 3 hrs ! i can belive it
NICE PAIR THANKS FOR THE INFO ILL CHECK , i have a buddy with a 300 x and we both took off full and i had under half when we checked and he had a quarter :eek: this sucks ! :mad: cant afford it , gotta have 150 bucks to go boating for the day
copper
11-01-2005, 10:19 AM
I had the same problem with a 200 XRI solder broke on fuel rail.#6plug was wet all the time,took me a while to find it,it was inside the box. Take it apart so you can pressureize the system with the box open.Or try to put some air to it. :)
PARKER RABE
11-01-2005, 10:22 AM
22 it burns alot no matter where u are ! bout 2 miles gal im figuring or worse :mad:
stvhelm
11-01-2005, 10:46 AM
I had this Idea about a 300 for next year but I think I just changed my mind:(
stvhelm
11-01-2005, 10:48 AM
hmm you know what? in the long run its probably cheaper cause I wont be tearing into it as much:o I hate decisions
1BadAction
11-01-2005, 10:50 AM
hmm you know what? in the long run its probably cheaper cause I wont be tearing into it as much:o I hate decisions

LOL... maybe you should stop with the 175psi on pump gas? :eek: ;)
PARKER RABE
11-01-2005, 10:52 AM
i just talked to tony brucato , and he gave me some ddt readings , 4.0 w o t , .95 at idle .................. im at 1.8 at idle and 4.8 at wot ,so ill start leaning it down , but how low do i go , i guess just keep checking the plugs ?
PARKER RABE
11-01-2005, 10:53 AM
its 150
Massbasser
11-01-2005, 10:54 AM
Something is wrong, that solder joint sounds like a good place to start, along with reading the plugs. Good luck!
22VelocityProMax300
11-01-2005, 11:57 AM
Parker, be careful changing the tps sensor for a reading below.94. This spring mine was at .95 and I had a lean sneeze when running just above idle.I had the tech set it at 1.04 ,it got rid of the lean sneeze and did not screw up my fuel economy.Frank
PARKER RABE
11-01-2005, 12:37 PM
1.04 at idle ? whats your wot ?
PARKER RABE
11-01-2005, 12:38 PM
when i idle in gear it pops and back fires at 600 rpm 1000 rpm it runs perfect !
22VelocityProMax300
11-01-2005, 01:19 PM
Parker, try increasing the voltage on the tps. I would be willing to bet you will correct the low idle popping. Frank
PARKER RABE
11-01-2005, 01:22 PM
sweet thanks
Toffen
11-01-2005, 04:37 PM
Hi!

I have been advised to set tps at 3,8V using a digital voltmeter. My engine use approx. 14 gallon at 4.000 rpms. 18,5 gallon at 4.500 rms. 30 gallon at wot.

Cheers, Toffen G