New engine but low power. 7.3 IDI

John Lahore · Apr 23, 2018

Just swapped out the engine in my 1990 SuperDuty for a rebuilt one from a 1994 van with about 20K on it.
The old one had 190K miles and a head gasket leak but ran fine.
The new one starts easily, idles smoothly, No smoke of any color, runs great but has about half the power of the old one.

It won't maintain 60 up a 5 deg grade with no load.

I did get my cold air duct hooked back up and changed out the old fan for an electric one that works great, only comes on when sitting in traffic.

When trying use more than 1/2 throttle the engine has a higher pitched kind of note, like it's struggling.
No black smoke.
Same old exhaust pipe with a muffler with less than 1000 miles.

Haven't checked the fuel filter yet.
Haven't checked the timing yet either.

John

Fixnstuff · Apr 23, 2018

John Lahore said:
Just swapped out the engine in my 1990 SuperDuty for a rebuilt one from a 1994 van with about 20K on it.

Just to rule out something simple, I suggest checking the THROTTLE CABLE to make sure the throttle is opening all the way.

I think that there are a couple of different lengths of throttle cables and the one from the Van may have been slightly shorter (?) in which case the one in your pick-up might be a little bit too long (?) thus it wouldn't be opening the throttle fully ?

Something like that is what I would look for first.

icanfixall · Apr 23, 2018

Throttle cable checking. Fuel filter and as always.. Timing. Many are real surprised when they finally time with a meter. Correct timing wakes up a low hp engine. Also please tell this forum what rig the replacement engine came from. Reason for the question is if the replacement engine was from a heavy duty international truck you probably have a 2800 rpm Governor speed now. U haul used the low rpm injection pumps.

John Lahore · Apr 23, 2018

The engine came out of a E350 van 1994.
Just went and checked the throttle, it moves all the way.
When I give it more than half throttle, the exhaust takes on a funny tone, kind of a high pitched resonance.
Next time I take it out I will hang a fuel pressure guage on it just after the filter
I don't have a timing adapter for this kind of diesel, I suppose I will need to take it to a shop?
Would it be bad to mark the current location and try it a few degrees ahead and back and see if it makes a difference?

Macrobb · Apr 24, 2018

Go for it. That's how I adjust timing anyway... and it seems to net me good results.

genscripter · Apr 24, 2018

I have a timing gun and ferret meter and I like to tweak my timing all the time. But really, knowing the exact degrees is kind of irrelevant for these engines. If I were you, I would mark the IP rotation, and adjust the rotation a bunch of different locations, and drive it around. Keep track of your boost, fuel usage, and power. Do this over and over, and once you find a good spot, keep it there.

Thewespaul · Apr 24, 2018

genscripter said:
But really, knowing the exact degrees is kind of irrelevant for these engines.

Macrobb · Apr 24, 2018

Thewespaul said:

In a way... it's true. If you have a new pump and injectors, the timing circuit(in the IP)isn't shot.... you can time "by the numbers". Otherwise, if you are dealing with worn bits... it's all out the window and you just play with it for best results.

79jasper · Apr 24, 2018

Timing is timing. Doesn't matter how worn it is. It's still going to fire. That's what you're timing off of, not the pump or injectors by themselves. The system as a whole.

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Thewespaul · Apr 24, 2018

Here’s a perfect example why timing by ear is not the preferred method. Last year’s Texas idi meet I timed a members truck that had issues smoking at idle and poor performance. The owner had messed with timing and gotten to were it performed best and smoked the least, but we threw the meter on to check how close he got. When I checked it the truck had almost 19* in it, adjusted it down and it was clear he had a bad set of injectors. Timing is more than just a useful tuning tool, it’s a lie detector for you fuel system. And saying that your actual timing degree is irrelevant is just not true, you can get it close by going by ear, but there is no replacing a timing meter.

Jason1377 · Apr 24, 2018

Thewespaul said:
Here’s a perfect example why timing by ear is not the preferred method. Last year’s Texas idi meet I timed a members truck that had issues smoking at idle and poor performance. The owner had messed with timing and gotten to were it performed best and smoked the least, but we threw the meter on to check how close he got. When I checked it the truck had almost 19* in it, adjusted it down and it was clear he had a bad set of injectors. Timing is more than just a useful tuning tool, it’s a lie detector for you fuel system. And saying that your actual timing degree is irrelevant is just not true, you can get it close by going by ear, but there is no replacing a timing meter.

Is a meter cheap as in not over $100 n can a person who knows nothing learn a decent amluam off YouTube vids n what would be the degree for idi n/a trucks

genscripter · Apr 24, 2018

Jesus h. I was not saying to time it by ear. And of course timing it with a gun is the best way, hence the reason why I spent the money to get my own timing gun and ferret meter.

I was explaining to the OP, who doesn't have a timing gun, how he could adjust his timing a bit from his current setup. Obviously, don't extremely turn your IP to something like 55 deg BTDC. I'm sure the OP understands that. But with making his current timing, he could adjust it and if it fails, he can revert it back to the original marking.

Not everyone who joins this forum has a lot of money or resources to fix their truck. The members of this forum need to lighten up a bit and be more helpful without snickering or being disrespectful.

John Lahore · Apr 24, 2018

Yes I will definitely not get wild and crazy with the timing and return it to where it is currently if there is any degradation in performance or mileage.
Since it starts and runs so well and idles so smoothly I am leaning towards thinking it's a lack of fuel at the moment.
It's a very dramatic limit of power with throttle, up to 1/2 it's perfect, after that, absolutely no change and no black smoke!
I should be able to test the pressure tonight when I get home.
Not touching the timing until I check the fuel pressure.

John Lahore · Apr 24, 2018

Jason1377 said:
Is a meter cheap as in not over $100 n can a person who knows nothing learn a decent amluam off YouTube vids n what would be the degree for idi n/a trucks

The setup seems to be around $400 for the adapter and digital timing light.

icanfixall · Apr 24, 2018

From reading this post from the beginning my guess is timing of lack of fuel. Lack of fuel can be anywhere from the tanks to the filter or weak lift pump. Even a crushed fuel hard line somewhere or that short rubber hose from the frame to the lift pump. Timing is the best way to know for sure you are getting the best hp and mileage from you engine. Doing it by ear is at best just a wild guess. Right now on ebay is a kent moore J33300 meter for less than 100 bucks.This is the meter I rent out for less than 100 bucks too.

New engine but low power. 7.3 IDI

John Lahore

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