A Couple of (Possibly Related) Fuel Problems

Engine, ignition, fuel, cooling, exhaust

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390xlt
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A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

I'm having a couple of issues, and I'm pretty sure they're both fuel-related, but I'm not sure if they have anything to do with each other, or if it's just a coincidence that they're both happening at the same time.

First, I'm having some pretty serious fuel starvation. I first started noticing it at highway speeds; I'd be cruising along just fine, but the engine would stumble every once in a while. I changed out both fuel filters and all the rubber hose and fired it back up. It ran fine for a little while (a very little while, like, less than 10 miles) then started doing the same thing except worse, and this time it was at normal around-town speeds. I pulled the filter on the fuel pump, and it already had some sludge built up in the bottom of the canister. Seems to me like I've got a really dirty gas tank, so it's time to pull it out and clean it, but if anyone has any better, easier, or cheaper ideas and/or suggestions, I would love to hear them.

Second, it hesitates almost every time I hit the accelerator. If I ease into it very slowly, it will do fine, and if I try to give it too much gas too quickly, it dies (a couple of times that's been accompanied by a backfire through the carb). Applying a "normal" amount of gas, it will act like it want's to die, but will come back with a little encouragement. I moved the accelerator pump arm to the outboard position, but that didn't seem to make a difference. Any ideas or suggestions?

In the month or so that I've owned it, the hesitation on takeoff has always been there, but has recently gotten worse. The fuel starvation is a new development, so I'm not sure if the two are related, but I definitely need to sort both of them out.
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 1972hiboy »

I dont think those problems are coincidence, i would describe them more as cascading problems, You may have a dirty tank which has been able to contaminate the fuel system and " stuff " has made it through to the carb in the form of fine particulates. I would pull the carb unit and tear down clean and install a new kit into it. you will probably find accumulation of stuff in the bowl area and accel circuit. causing the hesitation if the accelerator pump circuit has malfunctioned.
Rich
1973 f350 super c/s 460/c6 22k orig miles
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1972 f250 4x4 custom 84k og miles 390
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Re: A Couple of (Possibly Related) Fuel Problems

Post by basketcase0302 »

:yt: like Rich said.

Just a heads up on the tank also. Much easier done and a much better job if you take it to your local radiator shop where they can flush it out chemically then coat the inside using the same process they would a radiator. Look closely at where the pickup tube protrudes down into the tank, (it is fixed-you are unable to remove it unless you grinded the fitting loose then welded it back in). There is only 1/8" between the bottom of the 3/8" steel tubing and the bottom of the tank so it's very easy for any trash to clog it there when running / then fall back into the bottom when the pump isn't pulling / then pick up again when running / etc / on and on until you get the tank flushed. :thup:
Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

Thanks for the responses. I'll plan on cleaning everything from the tank to the carb.
I have grand illusions of going to a 4V carburetor in the future, so I was hoping to avoid putting too much work into this 2V, but given the cost, time, and effort required for that swap, I think I'm better off sinking a couple of hours and 20 bucks or so into this one to get it up and running for the time being.
Cleaning/rebuilding this carb seems pretty straightforward, but I'd be interested in any tips or tricks that you all have picked up along the way. I had a 2V Ford carburetor before on a 302, but that was years ago and I don't think I ever had it apart.
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 1972hiboy »

The autolite 2100 is really a great simple carb to take apart,clean and put back together. If you ever built model rockets as a kid getting some basic measurements accounted for in the carb will be a breeze. I should have mentioned yesterday as well, like Jeff said, if this is starting in the tank then everything you do will be void if the tank remains contaminated.
Rich
1973 f350 super c/s 460/c6 22k orig miles
1972 f350 srw crewcab special 390
1972 f250 4x4 sport custom 390fe Red
1972 f250 4x4 custom 360 FE " Ranger Ric"
1972 f250 4x4 custom 84k og miles 390
1971 f250 4x4 sport custom 56k og miles. 360
1970 f250 4x4 428 fe hp60 205 d60
Dont eat yellow snow.....
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

I'm not sure if I'll be doing it myself or taking it to a radiator shop (I need to analyze time and funds), but getting the tank clean is definitely my first step. Since the tank will be spending plenty of time sitting with cleaner in it and/or at a shop, I'll probably take that time and go through the carb anyhow, since it can't hurt to get it as clean as possible and put some new gaskets and rubber parts in.
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

Also, does anyone have a specific recommendation for a carb kit, or is one as good as the next?
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Re: A Couple of (Possibly Related) Fuel Problems

Post by basketcase0302 »

Here's the exploded view of the Motorcraft 2150 carb, (which I absolutely love-they are very dependable). As Rich said-I too think your gonna find the accelerator pump diaphragm on your carb with a crack or even a pin hole, (another recent thread here about the dangers / consequences of running ethanol based fuel in our older carbureted trucks / engines) and here is one. Ethanol eats away at rubber and I mean quickly, (I've repaired my step dads RV generator and mowers time and time again telling him to stop putting ethanol fuel in them but he continues to be hard headed so he pays the repair bill...
Get a good rebuild kit, (nothing made in china or japan-NAPA by choice for me if they can show "country of origin" to be the USA) and you'll be glad you did. Pay particular attention to the float setting to rule out fuel starvation. I didn't pick up on it the first time I read you post about how you changed "BOTH" fuel filters. I'd also run a pressure test on your fuel pump, (the pressure test gauge is cheap less than $20 which is also a vacuum gauge which you use a lot in diagnosing our trucks) to verify that your pump is giving you decent pressure. I'd also seen the rubber gaskets / o-rings on the canister fuel filter you've described on your truck prone to leaking, (causing a loss of suction / loss of pressure. GET RID OF THE CANISTER FUEL PUMP AS SOON AS YOU CAN and only run one filter between the "canisterless / filterless" fuel pump and the carburetor). Invest into a good fuel filter with a replaceable element-think of that $25 fuel filter as the life of your truck because that's just what it is. :wink:


Image
Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
Many Ford bumps / one 76' EB / and several dents through the years.
A lot of "oddball" Ford parts collected from working on them for 34 years now!
2008 Ford Escape 4 x 4
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

Thanks for the advice. I'll pick up a kit from Napa and hopefully get the carb sorted this weekend. I'm not sure when I'll be able to get the tank out, but I'm hoping to do that this weekend as well. Radiator shop quoted me something in the neighborhood of $100 and a little less than a week to clean and line it, and I'd love to get it up and running next weekend. Seems well worth that price. I think I'm going to stick with the current fuel pump until it gives me a reason not to (right now that filter gasket isn't leaking), but I'll go to a filterless one when the time comes to change it.
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

So it turns out that my tank was not only dirty, it was full of pinholes, too. I got a new tank, replaced the filters (again), cleaned the carb, and got everything back together, and now it won't start. It runs great on starting fluid, the bowl is full, and I've tried the mixture screws everywhere from 1.5 to 4 turns out, and it just won't run by itself. Sometimes I can get it to fire a few times, but that's it. I'm probably missing something obvious, but I'm starting to get frustrated and irrational. Any ideas?
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Re: A Couple of (Possibly Related) Fuel Problems

Post by colnago »

Fuel pump going out?

Jeff, you said:

"GET RID OF THE CANISTER FUEL PUMP AS SOON AS YOU CAN"

I've not heard this before. Do you mean in this case, or is this something in general that we should all look into? Are you suggesting an electric fuel pump?

Joseph
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

Pump seems to be working fine. After calming down a little bit, I took another look at it, and I think I've got it pretty close to figured out; the float was too low. The dry setting indicated by the rebuild kit was considerably lower than where it was when I took it apart. I set it anyhow and figured it would be close enough to get it running, but I guess it wasn't. There's still some fine tuning to do, but I think I've got a running truck again. Thanks to everyone for your help!
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Re: A Couple of (Possibly Related) Fuel Problems

Post by basketcase0302 »

"390xlt"]Pump seems to be working fine. After calming down a little bit, I took another look at it, and I think I've got it pretty close to figured out; the float was too low. The dry setting indicated by the rebuild kit was considerably lower than where it was when I took it apart. I set it anyhow and figured it would be close enough to get it running, but I guess it wasn't. There's still some fine tuning to do, but I think I've got a running truck again. Thanks to everyone for your help!
Sick as a dog yesterday, sorry I didn't come on the forum. :(
Did you have issues with the new tank? More specifically how well the fuel sending unit bolted into the tank? Had read a lot of guy complaining about the imported made tanks and that issue in the past. :(
Yeah anytime you've gotten fuel in the bowl and it won't start it more than likely is in the fuel circuit in the carb. If you've rebuilt it look closely now for air leaks, (which will be pulling in too much air-making it run lean-making your mixture screws almost useless). If you can keep the truck running a good quick way to determine this is grab a an of starting fluid, (you can use carb cleaner or even WD-40 but they can leave a residue on the carb making you then have to clean it off to seal a gasket). Spray the starting fluid to every gasket mating surface on the carb, (including the small accelerator pump housing and the base gasket where the carb meets the engine) with the engine running. Did it change the RPM's? Usually you'll hear an increase in RPM's-which will indicate where you have an air leak on the carburetor.
Sounds like your close.

And yeah Joseph I'm a stickler on the old FE canister fuel pumps as I've fought those O-ring gaskets way...too much before, (leaking air causing loss of suction of the fuel pump. A surefire way to diagnose the pump is by a fuel pressure, (which is usually also a much needed vacuum gauge for testing).
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Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
Many Ford bumps / one 76' EB / and several dents through the years.
A lot of "oddball" Ford parts collected from working on them for 34 years now!
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Re: A Couple of (Possibly Related) Fuel Problems

Post by colnago »

basketcase0302 wrote:... I've fought those O-ring gaskets way...too much before, (leaking air causing loss of suction of the fuel pump) ...
Hmmm, I wonder if that's MY problem. Mine can be a beast to start. Once she's running, she's fine. But I've always thought that I have a fuel leak-down issue somewhere. Maybe it's caused by the O-ring.

Hope you're feeling better.

Joseph
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Re: A Couple of (Possibly Related) Fuel Problems

Post by 390xlt »

Well, I might have spoken too soon. I went for a test run yesterday, and it ran pretty bad at speed, but idle was fine. Again, I figured it needed a little fine tuning, but I wasn't too worried about it.
Fast forward to today: it fired right up and idled great for a minute or so. Right as I was about to put a vacuum gauge on it, it stumbled a couple of times and died. Went to start it back up and it was doing the same thing as yesterday, not wanting to start, then if it does start, it won't stay running unless I'm giving it a lot of throttle.
Since I can't get it to idle, I can't test for vacuum leaks. I did use up a can of carb cleaner testing it before I took it apart and didn't find any leaks. I doubt if there are any now, but there's always a chance that something didn't get sealed up when I put everything back together.

PS The tank seems fine so far. Mounting holes for the sending unit and the cab lined up exactly.
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