A I checked with our buddy Tom Woodside at GMCOPO for his thoughts. Having done a ton of LT1 and LS1 swaps into earlier hardware, this is what he had to say:
"It sounds like a wiring problem at the fuel pump or a leak at the fuel-pump coupler in the tank. All this assumes that the correct fuel pump was used for the LT1 swap. If the truck originally had a LB4 TBI 4.3L V-6, then the pump will not produce the necessary pressure (around 42 psi) for the LT1's PFI injectors. To handle the fuel needs of the LT1, install a L35 CPI engine fuel pump, GM PN 25163473.
"Check the fuel pressure during key-up. The LT1 fuel rail has a pressure tap. Does it shoot up to about 42 psi? Does the pressure stay up during crank or drop? If it drops during crank, verify that the LT1 conversion wiring harness has the fuel pump power staying hot during crank. If the power is at the pump during crank and engine running, key on, and the fuel pressure is low or comes up slowly, I would drop the tank and inspect the fuel-pump coupler hose in the tank. These have a tendency to leak or disintegrate from fuel additives. If the coupler is OK, then I would swap out the fuel pump. The S-10 pumps are also affected by fuel additives and start to lose flow.
"As for your 'check engine' lamp, I would check codes using a GM Tech1 or Tech2 type scanner to make sure that you are not missing something. Also, is the LT1 harness properly tied into the vehicle ALDL connector? Is the scan tool communicating with the LT1? If you clear the unknown codes with the scanner, does the 'service engine soon' light then go out? Hope this gets your S-10 on the road, and you can reach me at 248.275.5828 if you have any additional questions."
Tom, thanks for the great advice. From my experience I'd have to think that your lamp could also be related to the functions that you removed. Whoever recalibrated your PCM missed one of the functions. Dig back through the functions you bypassed and check them off. Hope this has helped and gets you on the road very soon.Source: gmcopo.com
Can't we all just get along?Q I own a '00 Chevy Silverado and have put on a cold-air intake and a mass airflow sensor. Diagnostics say it is running too lean. Could you recommend a company/part that will deliver the extra fuel needed? Thanks.Nathan Schuetz
A You've run into a common problem of parts compatibility. Something in the component package between your cold-air intake and the aftermarket mass airflow sensor isn't making your PCM happy. If I had to guess, I would say it's the MAF sensor. Was it designed for your application? The specific frequency of the MAF must match the PCM's calibration. We would recommend standing on the company that made the MAF sensor and demand they send you a new one or the correct one. If it was designed properly, you shouldn't have any trouble codes or need to change out any other components to make your upgrades work.
Don't Shortcut Your LiftersQ I drive an '83 C-10 Chevy truck. Under the hood is a plain-Jane 350 stock crate engine from SDGC. It's equipped with a Performer intake, a 650 Edelbrock, headers, and Super 40s from Flowmaster. I just purchased an Xtreme Energy XE268H hydraulic flat-tappet cam. What kind of lifter and pushrods should I get? Thanks.Brad BrooksCorpus Christi, TX
A As you have probably read in other publications, flat-tappet camshafts have been failing with great regularity the past few years. A couple of reasons have come to light. First is the flood of low-cost, off-shore lifters being manufactured from inferior material and not up to GM tolerances. In the same timeframe, the oil companies have reformulated the motor oil, reducing the amount of zinc and phosphorous additives that provide high-sheer protection. Most of the OE engines now have hydraulic-roller tappets, which don't need as much high-sheer protection. And as engines wear and consume oil, these additives contaminate the catalytic converters, reducing their efficiency. Between the lifter quality and the reduction in additives in the oil, the cams got a double whammy and they were going flat on break-in.
We'd recommend going with high-quality lifters and pushrods from Comp Cams. They have very good lifters that meet the specifications of the GM tappets. Another trick is to use diesel motor oil for the break-in period of the camshaft. To be honest, we would run the diesel oil for the first 3,000 miles. These diesel oils should still have the high zinc and phosphorous content for at least another couple of years. This will give your camshaft plenty of time to get happy with the lifters.
If you have technical questions for Kevin McClelland, send him an e-mail at firstname.lastname@example.org.