Foxmxrcer

Hey guys, I've been lurking for a while and trying to learn the diesel ways. I'm a mechanic by trade, but we never really mess with diesels. Anyways, a few weeks ago I picked up a 90 w250 5spd, completely unmolested, completely stock, one owner, and well maintained. I drove it a bit, 2 tanks of fuel. When I bought the truck, it wouldn't shutoff with the key and he had a choke cable hooked to it. Over the weekend I installed a 3200rpm gov spring, and while I was messing with it I removed the fso solenoid, there was metal shavings stuck to it. I cleaned them off, tested the solenoid, and reinstalled it. Everything worked great. I had a few times where it wouldn't start and suspected the fso was weak, but continued to drive it. Before leaving work yesterday, I decided to rotate the fuel pin and noticed minimal if any difference while driving to the daycare to get my kid. When we went to leave, it wouldn't start. After sitting and messing with it(tried starting fluid as well) for about an hour and a half it finally started up, got home and parked it. Later I came out and gutted the fso, and went for a test drive. Felt like it had more power(suspecting it was never fully opening?), Came back home and let it idle, noticed it was smoking a lot. I'm not sure if the smoke occurs before the test drive or not. Messed with it today again after work, the smoke seems white with a slight grey hue, but more white then anything. Cooling system is not over pressurized, no signs of losing coolant. It idles a bit rough and seems to be idling a bit higher then usual, but it smoothes out in the higher rpm range. I returned the fuel pin to the factory location first, which sightly reduced the smoke. Then I cracked all the injector lines 1 by 1 listening for the changes in rpm to try and identify which cylinder was missing. I got to cyl 6, and the fuel was very frothy as if it had a lot of air in it, but it wouldn't bleed out. I'm thinking fuel injector stuck open, and compression being forced into the injector causing the air bubbles? Could it be a faulty pump? Anybody have any insight or further diagnostics to share? I plan to swap injector 6 to another cylinder and try cracking the lines again to see if the issue follows tomorrow. Also, I replaced the lift pump the day after buying it because it had a small leak.

Thanks, Jake

Rick 12v CTD

Any truck that won't shut off with the key but is considered unmolested and completely stock really have me wondering. The biggest reason the FSS fails and won't shut the truck off is due to the fuel screw being turned in. When you removed the shut down solenoid, did the rubber plunger have chunks missing from it or was it still completely intact? IT could have just gotten weak over time and failed as well. That's entirely possible

Refer to this for reference. Bear in mind, the missing rubber may not have been as significant as in the pictures
https://www.dieseltruckresource.com/...lenoid-117593/

Otherwise it sounds like you're on the right track.
Switch #6 with another and see what happens.

The reason I bring up the solenoid is because the little rubber pieces break off the shutdown solenoid plunger and work their way through the pump. My best guess is they end up at the delivery valves and it doesn't seem to be a complaint but it is possible that it could cause issues.

Now that you've gutted the shutdown solenoid I assume you no longer have issues with it not starting?

Also, there shouldn't have been metal on the shutdown solenoid plunger. Something may have gone through the pump or it could be worn too

Foxmxrcer

The truck has 300k miles on it and all the screws on the pump still had the anti tamper covers and locks on them. The screws holding the pump together where even still painted over when I dug into it.

The plunger was still intact, no chunks at all missing. I assumed it was either cocked, or the metal shavings on the end kept it from closing to shut the truck down.

I have not had starting issues with it since I guess the solenoid, but keep in mind.... Due to the smoke, I haven't driven it much.

I realize that in a perfect world there shouldn't have been metal on the plunger, but I do remember reading about other people having the same thing, with no issue. But I assume it's inevitably a sign that the pump is dieing, and only time will tell how much longer it will last.

Foxmxrcer

I probably won't get to mess with it until Friday night now. But I got to thinking about the metal shavings on the fso solenoid. Is that a sign that the pump is starting to go? I would assume there is no real way to put a time stamp on when it'll croak, but obviously metal shavings isn't a good thing. I remember reading about others finding it to when removing the fso, but obviously none of them posted in the same thread a few months/years later saying "oh hey my pump died". So more or less, anyone reading this that has had metal shavings on the fso, how long has it been since you noticed it? Did your pump wind up needing rebuilt? Still running strong?

Foxmxrcer

Update

I actually got some time today to mess with the truck. I was going to swap injectors, but after pulling #6 decided that wasn't necessary. I blocked off the return port of the injector, and blew through the supply port with my mouth and was able to blow through the injector and open it with about half my blowing force..... That seems a bit under spec . So, anybody have recommendations as to what injectors to go with? I'd like to keep my good fuel mileage, but more power wouldn't be terrible. I'll be doing research on the subject tonight, but real world recommendations are always nice. The injectors I removed are Bosch 937 KDAL 59P2 9522 946 245BAR and then the tip has 7782 stamped in it.... no idea what any of that means, side from pressure rating and Bosch is the manufacturer.

j.fonder

they're just stock 6x009 bosch injectors.

if you want a little more power, I would contact Mark at dieseltuff.com, he'll set you up with some good injectors at a real reasonable price. he'll only sell you what will work well with your truck too. good guy.

Foxmxrcer

I will check him out. But I think you have my truck confused with an IC truck. My injectors are 4 hole, and I've been trying to find the size, but I believe they are 4x12... But I've only found that in one source so far, can anyone confirm? I'll keep looking though.

j.fonder

Guess I should read the whole thread first, lol. In that case, I'd just find a local injection shop and have them gone through. Non IC (4x12) injectors are capable of 300+ hp

Foxmxrcer

Are they actually rebuildable at a reasonable price though? I did see that they're capable of high power numbers, but(assuming the logic transfers from gas to diesel) if the price is close to the same, I would think going with a more, smaller holed, injector would increase efficiency due to better atomization? Like going from 4x12 to 7x7 or 6x8

Rick 12v CTD

marine 370s are a stock injector for another application so they're typically fairly cheap to buy. They will make a bit more power and are the correct spray angle and everything. That's my recommendation.

Talk to Eric at hungrydiesel.com. He's a great guy who owns a first gen and knows them well. Plus his prices are as good as anyone.

To seal properly you will need the 7mm to 9mm copper seal adapter sleeves since the 370s have a 7mm shank and your non-ic motor has the 9mm shank injectors.

j.fonder

i'd just stick with the stockers and get them rebuilt at a local shop. Should run you no more than $200.

Foxmxrcer

So I asked a few vendors their recommendation for what injectors to go with. Unfortunately Each vendor gave me a different size. I decided to go with a set of 5x11's from DAP, in my head(weather its true or not) they should deliver a slight bit more fuel then the stock 4x12's, but still be efficient. I'm sure anything would give more performance then the 300k stock injectors due to how tired they were though. Hopefully they'll get here next week, and I'll report back.

j.fonder

i run those same injectors from DAP and they WILL NOT outperform stock Non-IC 4x12s.

Foxmxrcer

Really? I talked with.... Mitchell? On the phone and he said they would be a good replacement. And 4*.012=.048" and 5x.011= .055"..... So the bigger overall hole size would say more fuel.... So is it a flow difference? And when you say outperform, do you mean max allowable power, or same injectors in a stock truck, there will be a noticeable power loss going to the 5x11?

j.fonder

THats not how injectors are measured. The 5x11 has about .022 larger cross section than the 4x12 but the 4x12 will still outperform, stock for stock and max.