Checking for spark

[Big Country]

Hello all,

I was driving down IH-10 the other day and my truck just died. no sputtering, nothing. Towed it home, lifted the hood. and the first place i checked was spark. I took a plug out put it in the wire and had someone crank it. Someone told me i should see a spark. I didn't buy that but tried it anyway. No spark. Does this mean i don't have spark or is there an better way. i don't have a meter but also heard that if you take one of the wires off of the plug and put it next to metal on the truck it would arc. Is this true? I really don't feel like being shocked cuz it happened one time when it was really cold on another bronco and it split my finger open. Crazy!! Anyway i also checked to see if the throttle linkage being pumped was getting gas to the carb. i didn't see any. The pump was jsut changed 6 months ago, supposedly. I doubt my mechanic everyday something else goes wrong witht he truck. It was leaking during the summer and they wre supposed to replace it. i think they just tightened it. Anywho, someone else told me that teh fuel pump won't pump fuel unless the truck is on. They said there is enought fuel in the carb during cold start to fire the engine up. Again i didn't believe it but figured i would ask here. I need to find out if i need to replace ignition module or coil or both or if i need to replace the fuel pump or if by some crazy coincidence they all went out at the same time. Thanks!!

 

[Yardape]

Undo the fuel line at the carb, put the line in a pop bottle, crank the engine over a few times and it should spray gas into the bottle. (unhook the coil wire first just in case) if it does not, check fuel filter. Filter okay but still no gas? Be sure there is gas in the tank, dont trust your mind or the fuel guage. Farther tests on the pump maybe necessary, sometimes you can simply lick your finger and put it on the inlet side of the pump as you are cranking it over you should feel suction. If not get a piece of rubber gas line and stick it on the inlet side of the pump,stick the other end in a jerry can of gas, crank it over. If no gas sprays into your bottle, then its time to learn how to replace a fuel pump. As for the spark, unplug one end of the coil wire and place it approx half inch from where it plugs in, crank it over and the spark should be very noticeable. be sure there is no gas nearby when you perform this test or you will be learning how to fight fires as well. If you have no spark, then get ahold of Seabronc, he has a EVTM manual and he's not afraid to use it.

 

[Big Country]

Thanks for the suggestions. i am going to put some fuel in the tank this weekend. don't have time to do it during the week with 4 littles kiddies XMAS plays and sports and stuff. so you are saying that fuel should only spray while it's cranking? I wouldn't be able to tell by pumping the throttle with it off? That is good news if that is the case.

 

[Yardape]

The pump only pumps while the engine is cranking, has a lever that rides on a special camshaft lobe, the lobe forces the lever up and down, working a diaphram inside the pump, causing suction and forces the fuel out the otherside. The diaphram can tear over time and renders the pump useless. The carb can spray just by working the throttle if there is fuel in the float bowl, by the sounds of it you cranked it over quite a bit and that would have drained the float bowl if the fuel wasnt replaced by the pump.

 

[Yardape]

The pump only pumps while the engine is cranking, has a lever that rides on a special camshaft lobe, the lobe forces the lever up and down, working a diaphram inside the pump, causing suction and forces the fuel out the otherside. The diaphram can tear over time and renders the pump useless. The carb can spray just by working the throttle if there is fuel in the float bowl, by the sounds of it you cranked it over quite a bit and that would have drained the float bowl if the fuel wasnt replaced by the pump.

The "special lobe" is called an eccentric if you need to refer to it for some reason

 

[Big Country]

ok so if it is this pump it wouldn't be a tear off and put back on only would it? What should I know about changing the pump?

 

[Shadow_D]

Replacing the pump is as simple as removing the 2 lines that go to it, then remove the 2 bolts that hold it onto the engine and remove the pump from the motor. Pay close attention to the push rod that actuates the pump, if it seems to go into the motor quite a bit then you are golden if not then you are going to have to rotate the crank until the rod is in as far as it will go. Use your finger to push the rod against the eccentric, it should move "up" stop rotating the crank when it just starts to come back down. Now you can clean the old gasket off the mount surface and put the new pump in. Some thick grease will help with this as you need to push that rod all the way in, the grease will hold the rod in place for you to install the new pump. Tighten the bolts (DON'T FOR GET THE NEW GASKET) and reattach the fuel lines.

 

[firelt90bronco]

There is a nice tool to test spark that won't leave you with one **** of a spark. Its a spark tester, looks like a spark plug and can test spark, you'll find it at your local autoparts store.

 

[Seabronc]

There is a nice tool to test spark that won't leave you with one **** of a spark. Its a spark tester, looks like a spark plug and can test spark, you'll find it at your local autoparts store.

How about just using an old spark plug?

>-

 

[Broncosaurus!]

I do that all the time like you first described, If you think about it, there is nothing different. Ground the plug on the block by touching it like you said and turn it over, the spark is small and hard to see, darker lighting helps, but it is the same as inside the engine, but this way you can see the gap.

 

[Yardape]

Replacing the pump is as simple as removing the 2 lines that go to it, then remove the 2 bolts that hold it onto the engine and remove the pump from the motor. Pay close attention to the push rod that actuates the pump, if it seems to go into the motor quite a bit then you are golden if not then you are going to have to rotate the crank until the rod is in as far as it will go. Use your finger to push the rod against the eccentric, it should move "up" stop rotating the crank when it just starts to come back down. Now you can clean the old gasket off the mount surface and put the new pump in. Some thick grease will help with this as you need to push that rod all the way in, the grease will hold the rod in place for you to install the new pump. Tighten the bolts (DON'T FOR GET THE NEW GASKET) and reattach the fuel lines.

Fords dont have the seperate rod for the fuel pump, its a lever that is attached to the fuel pump itself. Sounds like someone here is a closet Chevy lover. LOL

 

[Shadow_D]

LOL sorry for that bad info, I haven't done a Ford mechanical fuel pump in a long time. I figured it was the same as my race car which is a chevy, I haven't found too many T-Birds in my area to use

 

[Seabronc]

Hey Seabronc, for some reason it is not letting me retrieve and print the iles attached. Can you attach them to my post in the forum? I believe i will be able to get to them there.

hey Seabronc,
question about ignition serries. what powers the ignition module lacated on the driver's side fender wall? I know from the module it powers the coil and so on but is that power to the module come from the battery to fuse box? Is there a fuse for the ignition module? I don't know if you have read my recent post but the thing died with no warning. I am trying to diagnose the problem but don't have a meter. thanks for any input

Yes power comes from the battery, but the ignition pulse for the coil is generated from the pickup in the distributor. I'm attaching a procedure from the 83 EVTM on how to determine if the problem is the module on the wheel well or the pickup in the distributor. You can make a few simple tools with parts that are easily available. It shows you how to build the tool in the procedure. Also I'm attaching a diagram of the start and run circuitry. If you have a Duraspark II system these are the diagrams for you. You may not have the throttle kicker module or the TPS. That depends on the engine.

Good luck,

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Here is the info you asked me to attach.