I have an 87 f350 custom 4x2 w/a 460 eng and 5 speed od trans.

Today I cleaned all the ground wires and positive connections. I then Cleaned the ground connection inside the distributor, I then put rotor and cap back on to test for spark. I pulled the wire off the coil and just held close to the coil and had someone crank the engine, I did'nt see the spark! but I did here the biggest bang (backfire) I ever herd.

My question is! What would make it backfire like that, so loud? I thought something blew up, Geeez!


Thanks

AL

 

Well if it backfired it must have fired, meaning you probably have spark. But I don't know what you're asking so I can't help you with your problem. Maybe a timing issue.

 

Hello Egor,

here's my problem

It's a 87 F-350 custom 4x2- 460 eng, w/ stock holley 4180 carb w/5 speed OD trans. Which has been sitting for 2yrs +.

Can't get it started


This is what I have done sofar!

1, pulled the carburator cleaned it and rebuilt it then set idle mixing screws in till seated, then turned them back out 2 turns. Then I ajusted the old plastic floats (dry) and replaced the power valve.
2, then I drained the old fuel, and replaced with new fuel, then blew the fuel line out with compressed air. (no more varnish smell)
3. Then I replaced the plugs, wires, dist cap and rotor.
4. Then I hand turned the eng till the #1 piston was TDC, then removed the distributor cap to see if the rotor was facing the #1 plug wire on the dist cap. It was, so I think the timming is very close?
5. Then cleaned all positive and ground connections.
6. I then! took a modified spark plug and plugged into the dist cap wire from the coil. Held it against the engine block and got a nice thick spark. I put the wire back on the distributor and pulled the coil wire off to see spark from the coil itself, and boom! I did'nt see the spark, But man! I thought someone got shotgunned wright next to me...lol.
7. I then looked into the carb, to see if it was getting fuel with cranking the engine, no fuel present, But! when I pulled the throttle lever back fuel was p**sing a nice stream into the carb from the primary pump nozzle.

and still no start, just alot of hissing, sneezing and some spitting of fuel from the carb. The spitting was comming from 2 tiny little holes on the top of the carburators main body, on the left and right side of the airhorn, I've never seen that before.

8. Then I did a fuel pressure and volume test, Results! less then 1 psi of pressure, then I ran the fuel into a 1 pint container for 20 sec and it filled the container...it's puzzeling!

Today I'm going to install an Electric fuel pump and an in-line fuel filter before the pump, as close to the fuel tank as I can get. But even so! if the pump is not working properly the darn thing should start when I pour fuel into the carb, I would think?

Any Help! Did I miss something or do something wrong???


Thanks

AL

 

Uh, Timing?

 

When you crank the engine without spark, or pour raw gas into the carb throat, you will load up the exhaust system with unburnt fuel. If you later get one or more cylinders to fire, even just a couple of pops, the fire and/or hot gases can touch off the fuel/air mixture in the exhaust sytem, resulting in a cannon-like boom.

Check your compression to make sure the engine hasn't jumped teeth on the camshaft timing chain.
Check that #1 is on TDC of the COMPRESSION stroke, not TDC of exhaust. It is possible the engine is 180 degrees off time

You can get a universal 12 volt electric fuel pump from Autozone for $10 to $20 or so. Add some 5/16 fuel hose to each end. Splice a filter into the suction line. Wire it up with some battery clips. Stick the suction end into a gallon can of gasoline, connect the pressure end to the carb, connect the clips to the truck's battery. This makes a very handy way to bypass the fuel tank, fuel lines, and fuel pump on a dead vehicle. It also comes in handy for transferring gasoline from one vehicle to another.

Another thing you can try is a few puffs of starting fluid (ether) into the carb, instead of trying to pour raw gas into the throat. Starting fluid will fire across a much broader range of mixture ratios than gasoline, and does not need to be atomized by the carb.

 

how did you test the fuel pressure?
Seems odd that you'd pass the volume test with no pressure.
Popa Tim

ps - if you stick a cork (wad of paper,aluminum foil...) in #1 cylinder spark plug hole and turn it over by hand (starter will turn too fast and you will rarely end up on the right cylinder), when it pops, that will be the compression stroke.. its a great thing to remember when some idiot turns the engine over on ya while you got the distributer out....LOL

 

[QUOTE=fefarms]
Check your compression to make sure the engine hasn't jumped teeth on the camshaft timing chain.
Check that #1 is on TDC of the COMPRESSION stroke, not TDC of exhaust. It is possible the engine is 180 degrees off time


it's now getting gas, I installed an electric fuel pump, and replaced the new plugs with new'er plugs and still no start. I don't get it!

Please! explain.

how do I know if I'm at TDC of the COMPRESSION stroke and not TDC exhuast. and if the engine has jumped a tooth how do I adjust that. and how do'es an engine jump teeth on the camshaft's timing chain?

thanks

AL

 

To check compression stroke, the Popa Tim cork trick will work.

The way I usually do it is to pull #1 spark plug (you do know that #1 is the front cylinder on the passenger side on Fords, right?) Conveniently, this is close to the starter solenoid.

Leave the key off. Pull the small wire off the start terminal on the solenoid. Use a screwdriver to momentarily short the start terminal to the battery terminal. The engine will turn maybe 1/4 revolution, less if you are quick.

Now put your finger over the #1 spark plug hole. Keep bumping the engine with the starter until you feel compression pressure against your finger. This is the compression stroke.

I will usually then use a wrench on the alternator pulley to turn the engine the rest of the way to the point that the timing marks on the balancer line up at TDC.

An engine jumps time on the camshaft timing chain when the chain wears out. Once this happens, the camshaft (and distributor) are no longer in the proper relationship with the crankshaft and pistons. The only way to fix it is to remove all the stuff from the front of the engine, remove the timing chain cover, and replace the timing chain.
It is unlikely this has happened to you, but something worth checking when you have a mystery "no start".

 

Thanks for that info. Compression stroke. got it?

Here is what I did!

I cranked the engine till the #1 piston was at the very top of it's stroke (TDC)

I then removed the dist cap to check and see if the rotor was pointing toward the #1 plug wire on the distributor, it was dead on. Then I cranked it over to see if the rotor was spinning, it was. The rotor did'nt seem to have any play in it, because I thought timing chain?

I then put a breaker bar on the hormonic balance and turned the engine by hand, to see if there was any play in the rotation of the dist rotor. either the bolt was loose our the timming chain is bad, because after about 3 short turns w/the breaker bar, I stopped turning it, because nothing in the distributor was turning. Maybe i'm missing something here, cause the rotor turns when the engine is being cranked over with the key.

I don't know anymore???

By the way what do'es ECM stand for, I for got, someone told me that if the ECM is not sensing oil pressure, That it will prevent it from starting?


Thanks again,

AL

 

Hey, I finally got it started...Hurray

It was the timing, I turned the dist 180* truned the key and whalla! Ignition.

But! even though I turned it 180*, do'es this still mean the timing chain still needs to be replaced? because it was 180* out??

Thanks guy's

AL

 

ECM stands for engine control module. The computer that controls the fuel injectors. It does not sense oil pressure. It will happily run your engine with zero oil pressure until it seizes up and will run no more.

GM computers have an oil pressure sensor that allows the fuel pump to run even when the fuel pump relay fails. But if the fuel pump relay works, they too will run the engine until it seizes.

If your engine starts and runs OK, seems to have decent power, and stays that way for a couple of days, there is nothing immediately wrong with the timing chain.

I cannot explain your symptoms of "the rotor doesn't turn" when you turn the engine with the breaker bar. Probably you weren't actually turning the engine.

If you turned the dizzy (or the rotor) 180 degrees and the engine started, the reason was that the engine was at #1 TDC of the exhaust stroke when you thought it was at #1 TDC of the compression stroke.

 

Thanks fefarms

Just need to know If I caused any damage by turning the dizzy, while it was at TDC of the exhaust stroke, because the they way it was set, the truck did'nt start at all. As soon as I turned it, the darn truck started right up??

 

I'm a little surprised you can even turn the distributor 180 degrees. On my 302 truck, the TFI connector comes off in such a way that the distributor will only fit in one position. It is obviously possible to lift the distributor up, disengaging the drive gear, and turn the rotor 180 degrees.

Installing the distributor (or rotor) 180 degrees off won't hurt anything, unless you crank it for hours and wash the cylinder walls off with raw gasoline. If it starts and runs OK now, check the timing and you are good to go.