hi, i am trying to start my 1968 bronco after 10 years of inactivity. please bear me out since i am not really very technical. Please pardon in advance my ignorance and lack of knowledge of technical terms and concepts.

my 1968 bronco is a 2 tank model. i have made some modifications, but none to the engine, which is a stock 289 with a MSR ignition from the PO. it ran fine 10 years ago. up until then i had kept it in good working order.

I could not find a troubleshooting guide for my exact situation, although some seemed distantly similar in some ways, such as this one:

1966 289 engine wont start - Ford Mustang Forum

also i do not really have anyone handy to assist me (beyond standing to the side of the bronco and watching, or pressing a pedal by hand).

so i improvised and did the following.

first i blew away all the cobwebs in the engine compartment.

i then replaced the battery with a new battery.

then i filled both tanks with 2.5 gal. of gasoline each.

i tried one tank-- cranked (using the ignition key) but did not seem to fire.

i toggled the gast tank valve under the seat, and then tried the other tank-- cranked but did not fire

then i tried removing the air cleaner and pouring gas down the carburetor. (is there a carb bowl? if so where is it since i could not find it?) when i looked into carb i seemed to see only a couple of 1/2" diameter vertical holes.) i seemed to get a very brief backfire which seemed to indicate ignition to me.

then i crawled underneath and observed that the valve was made inaccessible due to the forward (auxiliary) gas tank under the driver seat. so i loosened a connecting fuel line where the exit fuel line from the valve met the tube at the driver's side frame rail. when i did so, a small amount of gasoline came out of the fuel line. i reconnected the fuel lines.

then i tried to trace the fuel line forward towards the engine compartment. i could not find any fuel filter between the valve exit fuel line and the fuel pump (which btw looked relatively clean if not new).

I had someone else pump the accelerator pedal and watched the linkage move at the carb.

i tried to disconnect the fuel line from the carb fuel filter, but could not since it was too tight. so i got a large crescent wrench and unscrewed the carb fuel filter from the carb so that if any gas went through the fuel line, it would splash on the carb. Then i pumped the accelerator pedal 6 times. Then I looked at the carb, but it was dry. I repeated this for other gas tank by operating the gas tank valve but the carb was still dry.

I took off the carb fuel filter from the fuel line (which had loosened by now) and blew into it using my mouth. I was able to blow air through the filter easily. I thin put the carb fuel filter back onto the fuel line but left it disconnected from the carb and adjacent to it again.

I cranked the engine (about 6 revs) but did not see any gas come out of the carb fuel filter and splash on the carb. I switched gas tanks using the valve and cranked the engine but still did not see any gas come out of the carb fuel filter.

At this point I am wondering if the fuel pump is bad and needs replacing.

It is still not clear to me how the accelerator pedal operates. Is it in series with the fuel pump, in such a way that both must work in order to get fuel to the carb? Or does it work in parallel with the fuel pump, and if so, how?

(I could and might still repeat some of the early experiments with carb cleaner spray, but I tend to be pessimistic about any results of that in terms of getting the engine started with the assistance of carb cleaner. I have probably used about 40-50 cranks to get this far.)

I see many fuel pumps online but i thought i would just go to a local shop and get an inexpensive one if they are all warrantied for one year maximum(?). I see one online pump (Carter) (yeah i know) at $30 so that is much cheaper to me than a tow and a local mechanic's shop at $~100+/hr.

Along the way I noted that the old gasoline must have evaporated due to the old (at least 18 years old) locking gas tank caps from the PO not forming anything like an airtight seal. I wonder if there any modern locking gas tank caps that actually form an airtight seal that are available?

Thanks in advance for any help.

 

When an engine sits for even a few months usually the carb will go dry and it will be hard to get it started. That MIGHT be all you are dealing with, or you might have bigger issues.

And to answer one of your last questions first, the fuel pump and accelerator pump are in series, but do two different things. The fuel pump gets fuel from the tank to the carb. Without it the engine won't run. The accelerator pump squirts fuel from the carb directly into the air flow. This is to avoid the "flat spot" you'd otherwise get when you stomp on the gas. The engine will run without an accelerator pump (in normal operation the gas goes in through the low- and high-speed jets), but it will bog down when you accelerate hard.

Pulling the air cleaner off and pouring gas down the throat is a good first step. You won't have access to the carb bowl at that point (you'd need to disassemble the carb for that). The two holes you see are the "barrels" of the carb where the air goes in.

Pour just a little gas down the carb (it doesn't matter which hole, they meet below). If you're pouring it out of a gas can it's as little as you can, if you're measuring it, maybe a tablespoon (although that might be a little too much, I never measure it).

Essentially doing that will "flood" the engine, so hold the throttle wide open (the key to clearing a flood) and try to start it. If fuel delivery is your only problem it should start and run for a second or so. If nothing else is wrong you can just keep doing this, maybe 5 - 10 times. The fuel pump should be working those few seconds that the engine is running, and it should get gas up to the carb so it will run.

If that doesn't do the trick, take the fuel line off the carb and see if fuel comes out when it fires like that (you'll likely need help to do this). If you don't get any gas coming out, then either your fuel pump is bad or a fuel line is plugged.

If you do get gas coming out of the line, then likely your carb is gummed up. You might get lucky and get it to run by liberally spraying carb cleaner at and in it, but more likely you'll need to take it apart to clean it up well.

If you don't get any consistent (but short) engine run by pouring a little gas down the throat, then either you are pouring the wrong amout of gas (likely too much), or something else is wrong. If it's too much gas, crank it for a while with the throttle open and it should eventually clear. If it's something else, then you've got more investigating to do.

Good luck!

 

Old varnished gas is bad stuff. Have to do some investigation of the fuel tanks. It separates, draws moisture and turns back into a tar or varnish basically, coating the fuel tank walls and bottom of the tank. Plus rust.

Fresh gas, especially with ethanol, dissolves this crap into a nasty sludge that coats the tiny passages in carburetors and coats valves, stems and lifters. It will burn but then turns back into glue. Not good.

A good plan for now is to isolate or bypass the original fuel tank and use fresh fuel drawn from an external tank, a portable outboard boat tank works great. Something that sits a long time, a new fuel pump is always a good plan. A lot of times they will work OK for a little while and fail when put back on active duty.

Check for a good spark at one of the plugs and/or coil wire to ground. In order to fire reliably when installed under compression it should be a fat bright whitish-blue color. A thin yellow or red spark is no good. The coil wire should spark at least 1/2" to ground.

Keep the battery fully charged and recharge after a few attempts, an engine that won't start is a real torture test of the battery, solenoid, and starter. Let everything cool down for several minutes between attempts or you'll be throwing more parts at it sooner or later.

 

There are float bowl vents at the top of the carb as well. Small round or squarish (usually round on the Ford carbs I think?) holes that you can drip/dribble gas into without having to pull the top of the carb off.
This will avoid the flooding issue of dumping it down the throat, and actually let it run for quite a bit once it does start.

Worth thinking about anyway. Mechanical fuel pumps don't always like to renew their prime from just the cranking of the starter. And after sitting for so long, a mechanical fuel pump might actually fail completely and need to be replaced.
Especially a newer one with newer fuels.

The worst case use for a fuel pump is to be used for a short time, being almost new and then put away wet for an extended period. At some point, the pump diaphragm just fails outright and you can only replace it.

But with luck yours will still work. Filling the float bowls goes a long way to starting the engine.
Assuming it is indeed a fuel issue that is.

Good luck.

Paul

 

after 10 yrs sittin I'd wanna squirt a lill lube down the spark plug holes and just 'bump' the starter, take the VC off & look @ the rockers...U can bend all sorta stuff forcin it (push rods, etc)

 

Good point, some marvelous mysterious oil in the crankcase and fuel would be a good plan too.