Excessive Black smoke v-8 mack

[bron32]

Hello Guys

I have a 1980 superliner with a em9-400 v8 engine. This engine has started to smoke black when I am rolling down the road. It idles nice with no smoke ! Last year we rebuilt the injectors and injection pump.

I have taken the puff eliminator off......checked the air cleaner.......removed the hose in front of the turbo, which turns easy......checked the air to air.......and checked the suction pipe to the air cleaner.

The fuel pressure gage drops from 40 psi down to 18 #s then comes back up.......I do have one leaky injector fitting that I tried to tighten, but is still seeps a little.

The manifold pressure gage comes up when more power is required.

Any suggestions would be apprecitated.

Thanks

Byron

[fjh]

You need to preasure test the Whole intake system for leaks ! I have seen intake gaskets blow a chunk out! cap off the hose at the turbo side of the charge air and put regulated shop air into the hole where the puff limiter reversing relay WAS and crank it to about 30 psi you will likly find a cracked cooler or intake gasket blown out!

OR At idle run propane or ether around all of the intake system if ya hear and increase in RPM you have found your leak pay real close attention to the ends of the charge air core they tend to crack!

[e9500v8]

Fuel pressure is fine. How much manifold pressure is it making? And did it just start doing this ?

[220cummins]

puffer valve unhooked will make it smoke.

[BOB DINGSDALE]

We had that problem with E9 500 and theres a diaphram in fuel system that blows now and then.was a easy fix for someone that did it a couple of times.kind of like anoroid valve on a cummins.

[dds92780]

Ease into the throttle between shifts and then after a few seconds mash it down. This will eliminate black smoke which i am guessing is caused because you removed the puff limiter. You can still get good power if not better if you ease into each shift then slowly push the pedal down then ease into full throttle. I drove my old 89 R with e6-300 twin stick this way. It blew black smoke instantly when mashing the throttle so i drove with that method and kept up with all the other trucks. I hope this helps

[rsb502]

that is some good info just need a tad more, so far looking like intake system or fuel advance, is it smoking running at a steady rate down the road or just when pulling like gaining speed from a stop? You stated you removed the puff limiter, Im guessing you put a pipe plug in the end of the limiter where the air went in so the solenoid is still in the hole in the pump? It start when the limiter was removed or has been removed and did fine then just started all of the sudden? Last one, Which pump do you have, Ambac?

[bron32]

Thanks for all the replies.

The pump is a ambac. There was a air line from the pump over to the puffer. I plugged it at the at the pump and on the top of the puffer.

This truck only smoked, before, when you poured the the coal to it......now it smokes all the time rolling down the road. It was working fine

and everything that I have mentioned that I have tried is after this.

The muffler rotted out so I replaced it with a straight pipe.

The hood rubbed a hole in the air to air exchanger, 1st I j-b welded it but broke off.....so I thought it might have got sucked

into the turbo.....thats why I checked the turbo.....turns nice, got a piece of hose and gasket glue over the hole now.

The diesel injection shop says it sounds like lack of air getting to the engine.....thus the reason for black smoke, so if the intake gasket

was blown would this cause this problem ??

The maniflold pressure goes up to 18 #s if I hammer on the throttle.

Would a collapsed fuel line cause for a drop in fuel pressure ??

Thanks in advance for any ideas

Byron

[rsb502]

Manifold pressure is in the range it should be 13-21 per the Mack V8 tune up guide, but I have always seen it at the top end of that range in operation. I am guessing you have a charge air leak though, if you have a hole in it, replace it I realize you have a piece of rubber over it with gasket blue but I doubt that can hold 20psi of compressed air. I know they arent cheap but the engine wont run right if you are losing intake air anywhere on the way to the engine, I would guess with a load you should make about 20-23lbs manifold pressure, my 84 made 26 with a 500+ turbo on a 10% over pump and turned up governor, my 85 makes 18 bobtail with a turned up governor. You should remove the puff limiter from the truck intake if you arent going to use it, take the puff limiter valve off the intake and put in a 1/8" pipe plug go to the pass side of the firewall and there is an 1/8" ippe plug needed to remove the air line going to the valve. The puff valve can have internal issues and blow pressurized air into the intake if its been dead headed with a plug and the seals go out inside, I took mine off in about 5 minutes, thats cutting a bunch of wire ties, and painting the plug in my intake Mack Power Gray.