4.5 MPG on 1993 Pantera 550 Fuel Inj. 2 up - ArcticChat.com - Arctic Cat Forum

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post #1 of 11 Old 12-02-2005, 02:57 AM Thread Starter
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Sled: 1993 Artic Cat Pantera 550 EFI 2 up
ATV: 2004 Artic Cat 500 2 up
Fairly new to the forum but I was a Class A Mechanic for cars 20 years ago.
Quick replies would greatly be appreciated.

I know sleds go through gas as I owned one 20 years ago, but this seems like something is wrong with the sled.

I went out and only got less than 40 miles on my tank full which calculated out to 4.5 MPG (canadian gallon). It cost me $30 to get there and $25 on the way back all for a short trip on Sat. afternoon last year.

I test the compression, looked for fuel injector leaks, spark plugs looks like its running rich being slightly black. Compression reaches 90 psi on both cylinders on the 1st crank and about 115 on both cylinders and 3rd crank of engine.

I have not done a leakdown test as I do have an automotive cylinder leakage tester. I am taking it into a shop over the weekend, but I was a Class A mechanic 20 years ago and I want to see what readings I get before they tell me I need seals or not.

1. Can someone tell me how much or the max. pressure to put in for a leak tester.
Someone told me to watch out you can blow out the crank seals if too much psi.
I have quickly read a little and it seems they were talking about psi leaks from
3 psi to 15 psi leaks over a minute or something like that. Not sure what psi
they start testing at.

2. How much can it drop psi and how many minutes before you know the crank seals are leaking to bad? Example: excellent good bad replace seals

I am not sure what could cause the very very bad fuel comsumption.
3. Could seals make it eat gas?

A parts guy behind the counter said I should get 7-8 mpg but I am not sure if he is correct.
4. How many miles should I get on a tank full or better yet, how many miles/gallon?

Strangely when I called about bad gas comsumption to the Artic Cat Dealer they seemed to mumble, hym and haw that they could not check much but will take a look at it. They said I'm not sure what we could check out. I suggested the injectors, sensors, leak down test, etc. or what ever they recommend.
The shop is a dealer and has a large shop with motorcycles, ATV's and sleds.
With cars I use to put a scope up the tail pipe and measure raw Hydro Carbons (HC) (raw gas) coming out of the tail pipes. Set the valvles, timing, carb or fuel injection up all to lower the HC to beat out the spec.

5. What shoud they or me be cheking for bad gas milage.

Also the shop wanted to know if I want the sled going over for a check up for the start of the season.
6. What would they do for a check up and how much do you think it costs?

I have never had the snowmobile checked over by a snowmobile tech. and I know the sled handles like crap with no studs and carbides on the skis. I replaced the load springs on the back of the sled and that helped from bottoming out, but I know it should have a new front shock.
7. Should I get gas filled or just the original equipment shock. I weigh 240 lbs and my wife is on the back.

Thanks in advance for the replies.
Happy Sledding as its Snowing In Burford Ontario.
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post #2 of 11 Old 12-02-2005, 06:46 AM
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Sled: 15-ZR4000rr 2010 Polaris Shift 600 & 550
07-08 Mileage: 15
ATV: 2011 Arctic Cat HDX 700
2007 Mileage: 105
2006 Mileage: 400
My neighbor has a similar sled and experienced the same thing last year. I think they had some electrical part replaced and it fixed it.

If I see him I will let you know what it was.

"I'd rather be lucky than good"

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post #3 of 11 Old 12-02-2005, 07:56 AM
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Sled: 94 WildCat
Ok, first things first. Get a manual for the sled!! Theses systems work similarly to automotive fuel injection. They use engine temp. throttle position, RPM, Barometric presure, air temp, and fuel presure regulation. You need the manual so you have the specs for the componants. For poor fuel economy check the fuel presure, if it is high maybe you have a line restriction (return line) a failing regulator, or a leaky injector. Check the Throttle position sensor, is it set correctly for idle or is it telling the computer to richen up the mixture. There is a light on the computer that will flash if there is a fault code. A series of long and short flashes to give a code number. The computer will give one short flash when the key is turned on to indicate a good state of operation. With the manual, and your background, you should be able to get an idea of what is going right and wrong with the sled. Then start your search for parts to replace.
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post #4 of 11 Old 12-07-2005, 03:38 AM Thread Starter
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Sled: 1993 Artic Cat Pantera 550 EFI 2 up
ATV: 2004 Artic Cat 500 2 up
Zeek here,

Thanks for the reminder. I did purchase a manual and went through the manual testing resistance, voltages, leaky injectors, throttle sensor resistance, etc.
The only thing I did not check was fuel pressure. The sled does idle ok.
Sometimes it will flood on start up when cold and I remove the injector wires until she kicks over.

I talked to a friend who I bumped into a the Artic Cat shop when I took the sled in on last Saturday and he said they are pigs on gas as he has a 1996 dual carbs but I have a 93 fuel injection.
I see a reply that says 10mpg US which I could only hope for.
The shop will be looking at the sled today(Wed) or Thursday.

I was leary on the TPS (throttle positioning sensor) as the resistance was low when it should of maxed out a 5,000 ohms full throttle. It only read 3200 ohms but when advancing from an idle the reistance climbed smoothly.
I did have a hell of a time working with clutch springs to get rid of a dead spot from 30mph to 50mph when speeding up steady. I would have to hammer on the throttle to get past the dead spot. Working on the clutch springs and fly weights I got it better but not 100%. Maybe the dead spot is something to do with the fuel economy problem and only the clutch rebuild helped a little.

Also installing studs on track. Does it help with fuel economy much?

Hopefully shop will know or find something.

Thanks for the replies. (E-mail: keith@1stopfordogs.com)
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post #5 of 11 Old 12-07-2005, 09:58 AM
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Sled: 94 ZR 580
I always thought the 550 was good on gas, certainly better than the 580 I have. Now you are carrying a full load with two people on it, but it should not be that bad. This EFI system is very sensitive to battery condition and the one guidleine I have always heard is to replace the battery if the sled starts running poorly. Even if the battery test OK for charge a new one can make all the difference.

Your compression sounds good. Hold the throttle wide open and pull sharply until the needle stops rising, 5 times is usually good, on a cold engine, and 115 is reasonable. A fresh top end may show as high as 130, but the key, as you know, is for them to similar from side to side. If you had an air leak, intake flanges or crank seals, you would experience a lean condition, not a rich condition, and would likely loose a piston. The ECU flashes codes when the key is turned on to tell you of any system problems.

The other area to look at would be ingition, with focus on the stator. Stator problems can not be evident at idle and start up, but manifest themselves as the components heat up.

This is a piston port engine, so it is very simple. There are no exhaust valves or anything else to worry about. What RPM's is the engine and clutching running? You should probably have an engagement RPM of 4500 - 5000, with closer to 5000 being less boggy. The peak RPM should probably be in the range of 8200 RPM. If you are running so rich, or poorly to use that much fuel, then that is likely the cause of your bogging, rather than the clutching being too far off. If you are using that much fuel you are way down on power. If oyu are riding trails you should expect 100 - 120 miles per tank IMO.

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post #6 of 11 Old 12-07-2005, 12:07 PM
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Your not going to get any better advice than what you have here. These other posts are spot on for diagnosis.

The throttle possition sensor however, is extremely important and probably is the issue. If those numbers are wrong, it is telling the computer to add fuel for the conditions which do not exist. Symptom of mid range lag is indictative of too rich. Sparkplugs tell the tale. You have already solved the likely cause. Other lines of problems such as bad battery, which acts as a capacitor is good, and stator is good to. EFI need full power to run right. Low power will cause havic.

Personally, tho I know it is nice to know about it for future issues, I would take it to some super guru (and this ain't just john snowblower machanic) and let him run the diagnostics on it. Cut to the chase and get the machine on the road, asap. Shouldn't cost more than a couple hundred bucks and he might turn up a couple issues, which might give you fits to find without experience with EFI.

Otherwise, start by buying and installing new TPS, and work up from there.
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post #7 of 11 Old 12-10-2005, 05:15 AM Thread Starter
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Sled: 1993 Artic Cat Pantera 550 EFI 2 up
ATV: 2004 Artic Cat 500 2 up
Well I got it back from the Artic Cat Dealer. I guess they must be busy becasue they said I lucked out and it only cost me $35 to look at it. But they didn't find nothing so they stuck in in their door and kicked it back out. They said they saved me a million.
I checked to see if their was even a coolent thermostat present. Their was.
I put a thread into the thermosat, found a basking turkey thermomoter and ran hot water until the themostat opened up at approx. 125 deg. F. which spec is within 5 degrees. I wanted to make sure the sled was not running cold and using extra gas that way.
I bought a new battery today as it wasn't taking a charge from sitting over the summer. I wanted to get a new battery as its electric start and its worth the investment.
Upon getting it back home I had to charge the new battery. I made the mistake of putting the new battery in, hooking it up and then charging it in the machine.
Not suppose to do that with EFI but that has been done before on many cars and trucks with no problems. When the charger was on, I noticed the EFI control box flashing a light saying their was a problem with the TPS (throttle positioner sensor). The box gave 1 long flash and 1 short flash of the red light. This indicated an open or a short in the TPS. I checked the resistance and their was none at the closed throttle or wide open or anything in between.
Don't know if I did this from charging the battery while connected to the sled or things finally come to a head.
Now I am looking for a TPS for this 1993 Pantera 550.
I took the dam thing apart. Drilled out the rivots, removed the black silicone, removed the cover, looked for broken wire connections and could not find the broken connection and could not get it any further apart. Cleaned the rotation points and got a idle ohm reading but not readings during throttle.
Funny thing is I ran the sled into my garage and didn't feel any problem with performance meaning I will test the sled out today and see if it even runs.
If it does run without the TPS then that gives me a good sign this could be the whole problem.
The problem is Artic Cat shops only want to sell new sleds and might not have an experienced enough mechanic for electronic fuel injection. I just wanted an experienced guy to tell me what the readings on all the sensors should be reading.
I know the TPS spec is 850 ohms at idle and runs all the way up to 5,000 ohms at full throttle. My sensor reads zippo compared to last year.
I will call a couple of dealers today looking for a TPS and then check on Ebay and in the Sled local trader paper for parts.
I will also get a gauge to check the fuel pump pressure in making sure its not to high. I will also check the coolent sensors for resistance to make sure its not giving false readings to the EFI.

Any ideas on where to purchase a TPS as I kind of heard last year from the dealer I have to buy the whole intake unit. I am just back into sledding after 20 years and want to run a used sled for a couple of years before stepping up to a new one.
I don't mind spending $200-$500 on the sled but I already am spending too much money on this older sled that looked like excellent condtion when I bought it.
I don't want to be one of these guys that just ride around town becuase the sled is a big pig on gas.

Thanks for the replies.
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post #8 of 11 Old 12-10-2005, 04:17 PM Thread Starter
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Sled: 1993 Artic Cat Pantera 550 EFI 2 up
ATV: 2004 Artic Cat 500 2 up
Update Here,

Since the TPS was not getting any resistance and the computer code was flashing I removed the TPS and took it apart hoping to clean contacts for find a broken connection. Very tough to take apart with all the black silicone, rivits to drill out, "C" wire clip rings, etc. Got it 80% apart and the insulator board broke out with a piece of the flat resistor place contact. Junk now as it was junk before.

Here's the catch which is a help to me as I am hopping a new TPS will fix the 4.5 MPG problem.
Now there is no TPS connected as its unplugged.
I took out the sled and it runs great. Good performance.
Didn't even smoke a little on start up cold which is strange as it tend to smoke for a few minutes like running rich. Starts better, not trying to flood plugs on start up.
Originally the TPS manufaturer specs is 850 ohms at idle and full throttle 5,000 ohms. Without a TPS the sled should be running full out rich and I would see a difference in performance. But I don't. I'm hoping this means the sled last year was was running extremely rich having a a defective TPS but the computer did not show the warning code lights last year.

The earlier reply was interesting about 40mpg in the 70's as with my old SkiDoo Olympic 399 cc single carb, I beat the crap out of it and a 5 gal gas can still went a long way for milage.

I just got to find a TPS as I am having trouble finding one on Ebay, etc.
I heard rummor that a Toyota car might have the same. I will have to shop around for either a used one or a new one. Don't want to buy the whole throttle body.
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post #9 of 11 Old 02-14-2011, 11:25 AM
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i own a 93 ext 500 with dual carbs and this weekend averaged 4.6 mpg!! trying to figure out my issue too! one cyl runs perfect mixture the other slightly richer. otherwise lots of power, easy starts...not sure what the issue is!
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post #10 of 11 Old 02-14-2011, 11:41 AM
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Sled: 2000 600EFI Powder special, 2012 XF1100
10-11 Mileage: 2400
09-10 Mileage: 2500
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Another thing to check is your clutching. If your clutch set is not performing properly, it will reduce your mileage. A good way to check is to take a magic marker and draw a line from the top to the bottom of the clutch on the inside of the sheave (The parts the belt touches)
Then run the sled through it's paces. The line should be scrubbed off from just about top to bottom on both clutches. If you are seeing marks left, it means your clutches are not shifting out properly, and you should investigate the clutches further.

This may not be your problem, but since it sounds like you have somewhat eliminated engine problems, it's probably worth investigating
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