Between Omaha and Des Moines, 7 miles South of I80 | Kai - 4/10/2022 13:31 Hello everyone, Fairly new to working on diesels so please forgive any stupid questions. I've been attempting to diagnose an issue with my 1982 Ford B700 with a Cat3208T. Recently purchased and in need of love. This seems to be a place that has quite a bit of knowledge concerning this engine and it's quirks so I'm hoping I can benefit from some of that wisdom. As the title says the engine is stalling out when coming to stops or for slow corners if I let the engine idle. Sometimes it feels as if the prime pump has lost some pressure and priming will get it started. Sometimes it needs a shot of ether. if I pull the filter underneath the priming pump it is half empty. Left foot brake + accelerator keeps her running. There are quite a bit of air bubbles in the top of the glass water separator when I pull the throttle open. Not the little vapor bubbles I've seen in these filters before on other applications. I have a new priming pump coming tomorrow as I've read (on this site!) that when it fails it can be a culprit in the system pulling air in through weak seals and the seals on the back of the water separator are sometimes where it happens.
I have changed the primary filter, water separator filter, and secondary filter. Now to my actual questions lol.
1. Will air in the system recirculate if not bled out properly?
2. Will an electric pump between the primary filter and water separator help with air in the line?
3. I would like to replace the glass box type separator with a spin on. What model will be suitable for this engine?
4. Is increasing the idle slightly a potential short term workaround that won't be causing damage to the system?
5. What is the best way to check for leaks between the tank and water separator.
Thanks for any help, advice, warnings, admonishments or well wishes!
First, 3 fuel filters, in front of a CAT 3208 engine, is a lot and is rare = that 3208 fuel system, is basically "ALL suction" until it gets inside the fuel injection pump and governor areas. I would eliminate either the glass filter or the other primary fuel filter {currently, your glass filter is giving you clues [big air bubbles] to your possible culprit (sucking air in the fuel supply system)}
You could run engine, out of a clean 5 gallon bucket, of diesel fuel, and maybe connect right before the glass filter, and see if bubbles quit. (and how engine seems to run, also)
Answers, on some of your questions:
1: Small amounts of Air will bleed out of the front, right corner of the Fuel injection pump, IF the fuel return line is open, back to tank . BUT if there is air, in the Governor area, it can get trapped, and need to be bled manual, with a 9/16 socket, on the fuel rack cover [= don't loose that O-ring, if you totally remove that bolt, during bleeding].
2: It is best to have a totally solid, fuel supply system, that doesn't "suck air" or leak fuel, whether or not you install an electric pump, back by the fuel tank or not.
3: Get your fuel supply system down to 2 filters. (see first paragraph)
4: I agree with others, if an Auto Tranny, keep idle reasonable
5: Fuel sight glasses, plumbed into fuel supply system, then move to different locations, depending on what you find. (cheapest way to build them, is cheap vinyl clear hose, with some "push-on ends" that are sized for your current fittings) Remember, to watch a sight glass/hose correctly, the fuel flow MUST be going "up-hill" , so it kinda gets those bubbles "out" after you install the sight glass/hose assembly.
There are other issues, to examine, BUT first is to get Clean, Solid stream of diesel fuel, TO the injection pump (No Air !!!)
Are any "brass fuel T-handle valves, loose" ? (like drain valves on that glass water separator)
Is the fuel governor's throttle shaft loose and "sucking air" thru its rubber lip seal = I know it should be on the "pressure side" BUT when a CAT 3208 has a lot of fuel inlet restriction, those throttle shaft lip seals CAN and WILL "suck air" and aerate the whole fuel injection pump and governor area, too. (especially , under a harder pull)
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Cat 3208 stalls out under load at idle
