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Author Topic: fuel problems or under powered ???????  (Read 5581 times)

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Offline bombi

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fuel problems or under powered ???????
« on: January 13, 2014, 02:14:17 PM »
Hi All,

We have an odd use for a 1979 Ford Pinto 2.3liter, 2 barrel holly, with C3 transmission.. . we put it in a vintage "j5 Bombi" skid steer track machine for swamp and snow... ill try and add a photo.

They were made by bombardier in the 70's and originally this model has a chrysler flat head in it.

Seems to run fine on hard terrain, grass, gravel etc... but once you run in mud or snow it bogs right down... manually shifted into 1st gear, WOT and getting 1500 rpm...

compression test came in normal, originally thought it was simply that the 4cyl was underpowered for the application... .

now im not so sure...

as soon as you enter deep snow in 1st gear, WOT, engine sounds fine, but bogs down to 1500 rpm. however, if you back off the throttle and move around between 1/3 and 1/2 throttle you find a sweeet spot and the rpm will climb to 2000, then you can go back to WOT and it will run back up to a max about 4000- 4500 rpm. then somewhat randomly it will bog back down, sometimes 30secs later, sometime 5-10 mins later... then you start the cycle all over again...

thinking about going to an electric fuel pump but as its so intermittant im not sure what the issue is...

any thoughts?



RSM

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Re: fuel problems or under powered ???????
« Reply #1 on: January 13, 2014, 03:22:09 PM »
Sounds to me a possible fuel issue. If you had a way to check the fuel pressure when your issue starts to happen, could answer the question. Is the timing set correctly? Clean air filter? Fuel filter new or fairly new? While the engine is under a no load condition a bad fuel filter can still let enough fuel thru to let the engine run ok but under a heavy load will starve the engine. How clean was the tank when the 2.3 was installed? What's the condition of all the fuel lines? One thing I've done in the past is to get the engine to where it starts to mess up and then shut it off right away. I then pulled the top of the carb off to see how much fuel was in the bowl. If the fuel was low that would tell me if the float level was set correctly or if I had another fuel issue. What kind of gears are in the axles on that plow?

RSM

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Re: fuel problems or under powered ???????
« Reply #2 on: January 13, 2014, 03:30:43 PM »
Why does the map show you right in the middle of Lake Winnipeg?  :o   lol

Offline jtowndown

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Re: fuel problems or under powered ???????
« Reply #3 on: January 13, 2014, 05:18:49 PM »
maybe vacuum advance is messing up, or the vacuum line the the vacuum advance is loose. It sounds like a fuel problem, but with an intermittant problem that has no rhyme to it I'm going to guess that's what it is.

Offline 74 PintoWagon

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Re: fuel problems or under powered ???????
« Reply #4 on: January 13, 2014, 09:30:33 PM »
Sounds like it's running out of fuel??, put a pressure gauge in the line and run it and see what it reads when it falls on it's face, do you have adequate size fuel lines???..
Art
65 Falcon 2DR 200 IL6 with C4.

Offline bombi

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Re: fuel problems or under powered ???????
« Reply #5 on: January 14, 2014, 08:27:37 AM »
Thanks to All for the suggestions.

We are planning to add some fittings and get a fuel pressure gauge in to verify that avenue. any recommendation s on where to install the tee?

We beleive the timing is set correctly, but anything can happen in back yard mechanics ;-)
Air and fuel filters are new and clean, tried swapping in a new fuel filter recently too. Most of the fuel lines were replaced and the few existing ones "appear" to be in good condition. The tank did have some crap in it, but we removed it and did our best to clean it thoroughly.

Forgot to mention, we did add a new CDI box as well.

Dumb question.... ive heard some guys saying they've seen plug wire on two cylinders get crossed, but the seems to run "smooth" after adjusting the timing until it gets loaded up.... any truth to that? Anyone have a diagram so that we can confirm the plug wiring and firing order?

haha... dont know what happened with Lake Winnipeg... tried typing in Thunder Bay, Onatio a few times, but the map seems to be stuck...lol...

thanks again

Offline 74 PintoWagon

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Re: fuel problems or under powered ???????
« Reply #6 on: January 14, 2014, 09:02:30 AM »
Here ya go, put the gauge close to the carb..

Art
65 Falcon 2DR 200 IL6 with C4.

Offline bombi

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Re: fuel problems or under powered ???????
« Reply #7 on: January 14, 2014, 09:28:16 AM »
Great, thanks again.

Any comments on what the fuel pressure should be at the carb ?
5 - 7 psi ?

Offline 74 PintoWagon

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Re: fuel problems or under powered ???????
« Reply #8 on: January 14, 2014, 09:45:07 AM »
Never checked mine but I'd say 3-4 max lbs?, but whatever it is just watch for pressure drop it should be consistent.
Art
65 Falcon 2DR 200 IL6 with C4.

RSM

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Re: fuel problems or under powered ???????
« Reply #9 on: January 14, 2014, 01:03:47 PM »
You can run up to 5 or 6lbs of pressure or so without any trouble. The needle and seat material will hold the pressure but anymore than that and it won't hold. The fuel pressure guage can be plumbed in anywhere between the carb and fuel pump. I don't think a 4 cylinder will run very well with 2 plug wires swapped. You could that on V8's and they will run smooth at idle but not very well after that. Let us know what you come up with.

Offline 74 PintoWagon

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Re: fuel problems or under powered ???????
« Reply #10 on: January 14, 2014, 09:29:15 PM »
Well, don't have much experience with the Holley/Weber 2brl but everything I've read so far says 3.5lbs max?, checked mine and it's just a hair over 3.5, maybe I'll do a pressure check and see how much pressure it actually takes to open the needle.
Art
65 Falcon 2DR 200 IL6 with C4.

Offline amc49

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Re: fuel problems or under powered ???????
« Reply #11 on: January 15, 2014, 04:53:07 PM »
Anywhere from 3-7 psi will work, 7 is pushing it.

I know '80 2.3 carb has the metered power valve and maybe the '79 as well and you may be loading engine far more there than a car's weight ever does. You may need 100% power valve open, the later carbs are metered for emissions and do not do that. Way to know is type of power valve assembly, you can tell the carb from top, the early ones have a bi-symmetrical top flat where air cleaner mounts. The later one is not, it has a kickout on one side for the changeup in the car casting for that metered power valve or the later modulated one used on feedback systems for emissions. Those slowly open rather than either 100% open or shut like the early one does. Vacuum hose routing on carb to power valve area must be modded or at least very closely looked at as well or power valve will not work at all.

I ran into this once on my '80 2.3 while trying to find a severe mid rpm lean-out issue, it turned out the later power valve vacuum circuit was not opening the power valve I had installed. Once fixed it ran perfect.

Lesser weight (load) of car allows engine to still run with leaner than crap power circuit, bigger load of skidsteer may well need 100% power fuel all at once.

You can tell the metered power valve that screws into bottom of bowl from the off/on type, the metered one has a long slope on the center valve, the other one simply pops open or shut.

'We beleive the timing is set correctly, but anything can happen in back yard mechanics..... ......'
'.........after adjusting the timing until it gets loaded up.........'

Nothing personal but this sounds truly like back yard work and flat unacceptable. If I told you all the engines I've seen with holed pistons from 'experts' guessing this.......... .no insult intended at all but if guessing at the timing then get a light and set it correctly and probably your issue alone. One either knows EXACTLY where the timing is, or they don't and lost there. Need at least to check for proper centrifugal and vacuum advance, that alone could be the issue again. Make sure you are using the correct port for vac advance.

The new 'CDI' (it's not you know, simple inductive electronic only) box must have a blue grommet where the wires go under box. Other colors can mess with your timing in big ways, they are specialized for certain applications and coded by the grommet color. Just sayin' in case someone quickly snapped up one at the junkyard.

Many V-8s will seem to run fine with a certain plug wire disconnected as only 1/8th of the power is missing, they can even seem to idle smoothly, not so a four, it will be missing 25% power and readily noticeable.

Offline bombi

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Re: fuel problems or under powered ???????
« Reply #12 on: January 28, 2014, 09:46:33 PM »
Thanks again to all for the comments.

We installed the fuel pressure guage and it confirms this is not our issue. We have 6psi at the carb and it remains constant at startup, ilde, low throttle, and WOT even as its bogs down. Next steps we are thinking is to look into power valve and install a vacuum guage.

any other suggestions?

Also, just wanted to clarify a bit, as far as we can tell the timing is adjusted properly and we have no issues there. The idea was that we wanted to say that we are humble enough to consider all suggestions based on the sypmtoms we can observe.

With regards to power valves, how often do they "fail" ? and Also if we are to replace, any comments on the methods to select a power valve rating? We have reasearched a bit and found two methods, one suggests taking full manifold vacuum readings and dividing that number by two.... while others suggest taking the guage reading and subtracting 2 two

RSM

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Re: fuel problems or under powered ???????
« Reply #13 on: January 28, 2014, 10:46:25 PM »
I don't think it was suggested,but have you pulled the plugs to see what the engine is doing? If it's not a big hassle, run it till it bogs down then shut it off. Pull a plug or two and see what they look like. That will give you some insight as to what might be going on. If the porcelain is white then a lean condition is an issue. If you get a light tan color then fuel may not be the problem. If the plugs look good then gearing might be an issue. I asked before about the gear ratio on the drive axle but you may have missed it. Do you know what it is?

Offline bombi

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Re: fuel problems or under powered ???????
« Reply #14 on: January 29, 2014, 12:37:31 PM »
Gear ratio is 6:1 and we are running a C3 transmission, in first gear is 3:1 i beleive ?

Pulled the plugs today, bright white so we are runnning lean. I guess we will get our hands on a carb kit.

RSM

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Re: fuel problems or under powered ???????
« Reply #15 on: January 30, 2014, 12:50:09 PM »
Wow that's a low gear ratio. You may wind up jetting the crap out of that thing on the secondary side to feed enough fuel to help with the lean condition at high rpm. Not sure just the kit will do it. Let us know.