Chasing down smokiness and lack of power

[Oldstock14]

I can’t nail down what’s going on with my truck. I’ve got quite a bit of smokiness at throttle, it’s faint and white, you can really see it at night with headlights behind me. I’m also chasing down what I would describe as a ‘soft throttle.’ What I mean by this is, lower power than I feel I should be getting out of a new Walbro FRB13, 20k old Russ BB injectors, and a brand new IP from Justin. No turbo yet and the engine isn’t missing nor does the smoke smell like coolant. Just strong diesel.

The truck at moments feels real peppy, picks up quick and gets to 60 reasonably fast for a N/A diesel. But most of the time, I’m fighting the excess white smoke, higher egts than I’d like, and the lack of power; itll be pitifully slow sometimes. I also have noticed that when climbing a hill, the engine will have quick surges as soon as I crest the hill and start to come down the hill. Quick 1 second surges. It’s really odd.

I read white smoke and low power can be very retarded timing so I advanced it about two dime widths and it helped a bit but marginally. I’m going to advance it some more and see what it gets me. I’m also goin to be testing fuel pressure as well checking the walbro pump filter to see if it’s plugged up. I neglected to put in a pre filter to the pump and I’m wondering maybe if it pulled something into the 70 Micron screen. I’m going to put a pre filter in the line when I check the pump screen. I’ve already changed fuel filters up at the engine and the one I pulled didn’t have anything super nasty in it. When I did change the filters, it helped for about 3 minutes with the lack of power but then it went back to its normal behavior. So with all of this said, I’m curious if anybody else has anything I should check on top of what I’ve mentioned, or anyone has any input. After the injectors, and new pump, I’m really annoyed this thing is giving me problems still. These old engines are a labor of love but sometimes I want the ****** thing to operate as it should lol. Let me know what y’all think.

 

[Nero]

Which pump do you have? 80cc? 90cc? Sounds like too much fuel, not enough air.

 

[Oldstock14]

Which pump do you have? 80cc? 90cc? Sounds like too much fuel, not enough air.

90CC, turned down 2 flats at the recommendation of Russ.

 

[Nero]

White smoke in this situation is probably raw fuel slowly burning off in your exhaust pipes. You say the injectors are 20k old, were they sitting for a long period of time? Have you tried running any fuel cleaner/atf through your system?

I have a few hypothesis's

Sticking injector causing poor atomization
Poor compression
Not enough air
Air in fuel

I'd start with the easiest, hot soak the pump/injectors in a good fuel cleaner. Standadyne, liqui moly, diesel purge, your choice. Give it a good overnight soak, then drive the ballz off it the next day, see if it clears out.

I had a stuck open injector when I assembled my engine, and it filled my manifold and down pipe with raw fuel. It smoked white until it all burned out. Took a few miles of hot driving, just to give you some perspective.

 

[The_Josh_Bear]

First of all, your engine SHOULD run the way it's designed, there's nothing wrong with wanting that! I'm with you and I'm sure there's a solution to this.

Second, @Nero has given a good start along with what you said you'd do. Stuff clogging the fuel supply is definitely suspect. Once I had a cheap electric pump with a cheap little pre-filter on it and it caused me all kinds of heck before I remembered it and realized it was clogged up...

Third, timing is everything and not having a meter on it makes it really hard to get a starting point. The lines on the IP and engine are just to get it running, they don't seem to be calibrated in any way and can vary by like 10*. It's pretty sad, really. Got any members around you with timing gear? I'm not sure about the current state of timing adapters available online.

I guess the fact that it runs well at times is a good sign; what conditions does it run well under? I.E. First start of the day; before the high idle shuts off but not after, randomly while hot, etc.
Surging at the top of a hill is really odd but maybe you're sucking air when running flat? That would be totally strange but that's why we're here!

I was going to say that a 90cc, even turned down 2 flats, will be over-fueled for N/A. But you say it runs really well at times so let's leave that alone for now. Changing that max fuel screw will also change timing, and the less you adjust at once the better you can narrow down the issue.

Sticking injector causing poor atomization
Poor compression
Not enough air
Air in fuel

I believe not enough air still comes out black, but yes on the other 3.

 

[Nero]

Too much fuel burning comes out black. Too much unburnt fuel comes out white. Plus smells of raw fuel.

I guess do a sniff test? Just dont stick your head in the exhaust pipe

 

[Lawrence Koepke]

My '91 F350 with the 7.3 IDI started emitting clouds of white smoke with an odor of diesel on startup, first running on 7 cyliders, then smoothing out after a few seconds. The smoke largely cleared up after a short time. However, it still blew out white smoke under throttle. I had added a Banks Sidewinder turbo, a water-air intercooler (of my design), and water-methanol injection system (Snow), so I decided to send the engine (only 95K original miles!) to Justin at R&D IDI Performance to have him rebuild it with turbo components, his IP and his cam, allowing me to toss the wastegate and feel confident in the engine's integrity pulling my 5th wheel over long mountain passes (Russ also upgraded the turbo). Justine found a puddle of diesel on a piston when he opened the engine. It turned out an injector (with about 40K miles on it) was seriously leaking.

I suggest checking your injectors. I remember Justin telling me mine failed a pop test, and was leaking fuel continuously.

 

[Nero]

Startup smoke should last seconds at that. Anything more and stumble at first start I would suspect air intrusion on a return cap or a bad injector leaking down overnight. Low mileage injectors can fail too. I had one fail out of the box new.

 

[12pilgrim]

My '91 F350 with the 7.3 IDI started emitting clouds of white smoke with an odor of diesel on startup, first running on 7 cyliders, then smoothing out after a few seconds. The smoke largely cleared up after a short time. However, it still blew out white smoke under throttle. I had added a Banks Sidewinder turbo, a water-air intercooler (of my design), and water-methanol injection system (Snow), so I decided to send the engine (only 95K original miles!) to Justin at R&D IDI Performance to have him rebuild it with turbo components, his IP and his cam, allowing me to toss the wastegate and feel confident in the engine's integrity pulling my 5th wheel over long mountain passes (Russ also upgraded the turbo). Justine found a puddle of diesel on a piston when he opened the engine. It turned out an injector (with about 40K miles on it) was seriously leaking.

I suggest checking your injectors. I remember Justin telling me mine failed a pop test, and was leaking fuel continuously.

What did that rebuild cost?

 

[The_Josh_Bear]

I suggest checking your injectors. I remember Justin telling me mine failed a pop test, and was leaking fuel continuously.

I agree.
Just cause I've been known to think outside the box a time or two, I've actually pop-tested my injectors IN the engine. Twice! Saves a bunch of time if they are OK.

Edit: And if you find a bad one, you only need to pull one, theoretically.

 

[klook]

Mine also has come and gone with how it runs. Lately it has been perfect. But 2 weeks back it ran poor for several days in a row. It felt like it was running on 7 cylinders. I have to add the correct amount of cetane booster to make it run right. I ran heavy Seafoam, some PS injector cleaner, some tank algae cleaner from PS, and my normal 1/2 ounce to the gallon cetane booster. I am using the Pilots brand at the time. This last week it has ran so smooth it is like a gas engine, quiet and just hums.

 

[Lawrence Koepke]

My custom rebuild cost was around $12K, which included close to $2K for shipping from CA to WY and back. Justin charges $6.5K for a basic custom engine build. I had just about everything possible done, i.e. turbo rods & pistons, stronger head studs, his IP, injectors, cam, & fuel rail, etc. Justin's website, https://idiperformance.com/, is full of goodies & prices. AFAIK, his is one of only two operations in the country that custom-build these engines for you (I have no idea who the other is). He is a real artist, he takes his time and does beautiful work.

Josh_Bear: How did you pop-test your injectors in the engine?

 

[Old Goat]

I stopped by his shop lil over a year ago. Has a full
machine shop for engine rebuilds to his injection rebuild
area. You have the money, he has the goodies.

Have you figured out what kind of mileage you are getting
with all this new power?


Goat

 

[Oldstock14]

My custom rebuild cost was around $12K, which included close to $2K for shipping from CA to WY and back. Justin charges $6.5K for a basic custom engine build. I had just about everything possible done, i.e. turbo rods & pistons, stronger head studs, his IP, injectors, cam, & fuel rail, etc. Justin's website, https://idiperformance.com/, is full of goodies & prices. AFAIK, his is one of only two operations in the country that custom-build these engines for you (I have no idea who the other is). He is a real artist, he takes his time and does beautiful work.

Josh_Bear: How did you pop-test your injectors in the engine?

You can buy/make pop testers online. I’m about to do so. There’s also plenty of write ups on how to tear down, clean and shim your injectors for good pop pressure. If you’re sitting on a stockpile of injectors like I am, it’s good to know how to tinker on them, in my opinion.

 

[Oldstock14]

I thought I gave an update on this whole debacle but it must not have posted. Hillbilly internet can be hit or miss. I wasn’t able to do any work on the truck this last weekend, worked an 18 hour shift over Friday night into Saturday afternoon and I was recovering from that all weekend lol. I’m going to do my checks and wrenching and I’ll post up what I find and figure out. Thank you all for the responses.