Need help with a 4.9

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Dec 11, 2016 | 05:46 PM

Maddog34

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Need help with a 4.9

I have a 87 F150 4.9 I changed ignition modulator also change the coil the distributor cap the bug plug wires and I have fire and fuel and it will not run just crank over could someone help me

Dec 11, 2016 | 05:57 PM

timbersteel

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Was the truck running before you swapped anything out?

What's the history of the truck?

Dec 11, 2016 | 06:07 PM

Maddog34

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Yes I put new exhaust on it started it up to check for leaks turn it off came back to it two days later never started again so I started eliminating possibilities

Dec 11, 2016 | 06:09 PM

Maddog34

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The motor supposed to have low miles on it

Dec 12, 2016 | 11:37 AM

moonley

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What was the process you used to determine you had spark and fuel?

Try spraying some carb cleaner through the throttle body while you are cranking and see if it fires; if so you likely have a fuel problem. If not, you likely still have a spark issue.

Dec 12, 2016 | 01:00 PM

Maddog34

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Pulled spark plug out turned it over and spayed starting fuild in throttle body

Dec 12, 2016 | 07:46 PM

moonley

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if it won't even fire on starting fluid, and you have spark on ALL cylinders, then it's either a timing issue or a compression issue. Did you move the distributor when you replaced all the parts? Did you replace the wires in the correct firing order AND the correct orientation on the distributor cap (is the rotor still pointing to the #1 plug when you are at TDC on the compression stroke)?

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Dec 13, 2016 | 09:06 AM

nnero

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From: NY (not the city!!)

Turn it over with distributor cap removed and watch to see if the rotor spins.

Dec 13, 2016 | 08:19 PM

#10

moonley

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Quote:

Originally Posted by arse_sidewards

An engine with too little compression to idle will start fairly easily on starting fluid if spark is present. I wouldn't spend too much time looking for a compression issue if it ran recently.

While I agree that he should look at spark and timing first, there are a number of mechanical failures that could result in a no-start situation with low or no compression in one or more cylinders.

Dec 14, 2016 | 07:25 AM

#11

FordMac1

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I just posted a thread titled, "4.9L i6 300 Hesitation/Stall/Rough Idle". Check that out. I agree with comments on the timing. There's a great youtube video for replacing a distributor - search "1987 Ford F150 I6 Damper, Distributor, Timing, and Start Part IV". Im currently experiencing similar problems so I hope this info will help you out!