Auto Service World
Feature   May 1, 2002   by Rick Cogbill a.k.a. Slim Shambles

Injector Gadget

Quigley walked into the coffee room with a clipboard full of papers. "Susie Picket just had her '88 S-10 pickup towed in." He handed a hand-written note to Basil. "It quit on the highway, and hasn't r...

Quigley walked into the coffee room with a clipboard full of papers. “Susie Picket just had her ’88 S-10 pickup towed in.” He handed a hand-written note to Basil. “It quit on the highway, and hasn’t run since.”

The name sounded familiar. “Isn’t she the daughter of Professor Picket?” I asked. Professor Picket taught the Pre-Apprentice course over at the Trade School, where he was known as Fix-it Picket. According to local legend, he’s never been stumped yet by an automotive problem.

“That’s right,” Quig replied. “The Prof. has been working on this for a week, but now it’s our turn.”

That worried me. If Fix-it Picket was stumped, then this could get ugly. Basil read over Prof. Picket’s copious notes on the steps he had already taken to address the problem. He adjusted his reading glasses. “Looks like fun, Slim,” he warned. “The truck cranks, starts, and then quits after a few seconds. According to his notes, old Fix-it has checked everything I would have checked.”

“Well, let’s start over,” I suggested. “Maybe he overlooked something.”

The S-10 had a 2.5 4-cylinder motor. There was good spark at the plugs, and we had lots of fuel pressure. By adding artificial fuel (in the form of gasoline or propane) we could keep it running, so everything pointed to an injector or injector control problem. That’s where the fun began. Basil checked the injector wiring harness with a noid light. “We’re getting a good signal here,” he said. “I’ve checked the wiring connections back to the computer just be sure, and they’re good.”

“What’s the resistance on the injector itself,” I asked. “Maybe it’s shorted out.”

Basil hooked up his test meter. “Well within specs,” he replied. “It’s odd. We get a little squirt of fuel at first, but then it stops.” He reached for his coffee cup. “When I run the lab scope with the injector harness connected, I get a strange wave pattern. Not quite the sharp, square pattern I’d like to see. I wonder if we need a new injector here.”

I mulled that over. “Well, we’re on a tight budget. Why don’t we send this injector over to Injector’s Inc. They can bench-test it, and if they say it’s shot, I’ll break the news to the Prof.”

So that’s what we did. I was halfway through my third afternoon donut when Quigley came back. “I hate to spoil your appetite,” he said, “but according to Injector’s Inc., there’s nothing wrong with this part.”

Basil stopped chewing. “Are you sure?”

Quigley placed the offending part on the table. “The windings have the right resistance, it passes the flow test, and the spray pattern is good.” Funny how a piece of metal and wire can ruin your appetite.

I called up our Tech Line and explained our problem to Hal. “So the only clue is the injector patterns,” he mused. “Why don’t I fax you some sample wave patterns of what a good injector should look like. I’d say that if it doesn’t match up, you should try a new injector anyway.”

The patterns Hal sent didn’t look anything like the ones on our lab scope, so I had Quigley start looking for the best price on an injector.

“I’ve found one!” he exclaimed a few minutes later. “It’s coming from Backyard Buddies, the discount store.” I raised my eyebrows. “Hey,” Quigley added defensively, “it’s half the price our usual supplier quoted me.”

“Yikes, Slim,” said Basil. “Are you sure this is a good idea?”

I shrugged. “We could try it. It may not last the life of the truck, but at least it will run.”

But I was wrong. The new injector didn’t fix a thing, and the lab scope pattern was the same as before. Prof. Picket came by later, and after a long discussion, he hauled the truck back home. I said I’d call if I had any more ideas.

The next evening we attended a fuel injection course sponsored by our supplier. After the seminar, I approached the instructor with our problem.

He scratched his chin. “Sounds like you’ve covered the bases. And you’ve tried a brand new injector?”


“Uh, not exactly,” interrupted Quigley, sheepishly nursing his coffee. “It was a rebuilt.”

“A what?!”

“I didn’t notice until later, but the invoice from Backyard Buddies listed the injector as a ‘Reman’ part. That’s why it was so cheap.”

The instructor patted my shoulder sympathetically. “Better try a brand new one. I believe your usual supplier keeps them in stock.”

I called up Fix-it Picket the next morning and gave him the details. He said he’d give it a try.

An hour later he pulled up to the front door in the S-10, grinning from ear to ear. “So,” I said, “it looks like the remanufactured injector had the same internal problem as your old one.”

“Yep,” he said proudly, hitching his thumbs through his suspenders. “I dropped in the brand new one, and now she purrs like a kitten.” He put the truck in gear. “I fixed another one, Slim. So far, my record is perfect.”

As he drove off, I reviewed my own record, and it was perfect, too. When it comes to solving problems for free, I’m batting a thousand.

(Thanks to Mark Purdey of The AutoPro Alignment Shop in Kamloops, BC, for this month’s technical problem.)

About The Writer

Rick Cogbill is a freelance writer living in the Okanagan valley of Southern British Columbia. A licensed technician with over 25 years in the automotive repair industry, including ten years as a shop owner, Cogbill creates his comic scenarios with Slim, Basil, Tooner, and The Bean out of actual case histories. “What you have just read is true,” drawls Slim Shambles. “Only the names have been changed to protect my hide!”

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