Black smoke when starting.

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Jun 11, 2016 | 12:44 AM

Rawo Walles

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Black smoke when starting.

I have a 89 F-250 with a 351w. When I go to start the engine it blows a little black smoke out the exhaust. Is it cause of old oil? I recently bought this truck and I use it around a farm. I dont know the miles because the dash cluster dose not work. It will only show the RPMs. Anything similar happen to anyone else?

Jun 11, 2016 | 09:48 AM

bmxerbrett

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I would guess it's from unburned fuel during the startup process. I wouldn't worry about it.

Jun 11, 2016 | 12:53 PM

'89F2urd

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Is the check engine light on? How does it run?

Jun 11, 2016 | 03:30 PM

JKNW

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Black smoke is unburned fuel, most likely you have an injector leaking down while the truck is sitting.

Jun 11, 2016 | 07:09 PM

ArdWrknTrk

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From: EXTREME southwest CT

Quote:

Originally Posted by JKNW

Black smoke is unburned fuel, most likely you have an injector leaking down while the truck is sitting.

X2 on this..

Jun 11, 2016 | 07:47 PM

'89F2urd

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Yep that's where I was heading.

Jun 11, 2016 | 10:29 PM

Rawo Walles

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It runs fine. It has trouble starting due to solenoid/relay or starter issues. But yes the check engine light is on. The wiring is a mess under the hood, but im really not concerned about that. Ultimately i have other plans for the 351. I was just curious if black smoke was particularly bad for the engine.

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Jun 12, 2016 | 02:05 PM

JKNW

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It's not great for it, if there's an injector leaking down that means that it's also washing away the oil that lubes the rings.

Jun 12, 2016 | 04:19 PM

#10

87 XLT

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From: SoCal

On most Fords checking fuel pressure is as simple as checking tire pressure. Screw on a gauge start it up turn it off & see if the pressure holds steady. If it does'nt something is leaking

Jun 12, 2016 | 05:30 PM

#11

'89F2urd

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You can also do a hard downshift engine brake test. If you downshift to ~3000 rpm and let the engine slow you down there should be no fuel injecting, so if it stumbles and pops and is not smooth, you have a leaking injector. In a downshift, it should be smooth as though the key was off.

Jun 16, 2016 | 09:35 PM

#12

Rawo Walles

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Ok, thanks. This has been helpful. Curious question. How do I show my vehicles and specs under each post?

Jun 17, 2016 | 12:19 AM

#13

Lead Head

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From: Rhode Island

You add it to your signature in the user control panel.

Jun 17, 2016 | 06:20 AM

#14

My4Fordtrucks

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Quote:

Originally Posted by Rawo Walles

It dose run fine. Check engine light is on but thats because the wiring under the hood is a nightmare. Also because it was originally an automatic C6. Now it is a 5 speed ZF S5-42.

The PCM doesn't control a C6 and wouldn't know you now have a 5 speed.

What codes are in the system?