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About east3021

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  1. Glad you got it sorted out and thanks for updating your thread. I have two 98 models, one a Z71 and the other a two door Tahoe. I did the MPFI on both while doing the intake gaskets. I noticed a better throttle response in the truck but no noticeable difference in the Tahoe. I suspect that most of the improvements noted are in comparison with stock injectors that were in marginal condition. You don’t tend to notice a slow decline in performance until the bad part is replaced. I’ve usually averaged 11-12 mpg in both of these. The injectors made no difference there in my case, but others may have different experiences.
  2. I’ve never found a good answer for that. The manual just says it’s regulated to 60-66 psi with engine off (no vacuum) based on the spring pressure of the regulator. I suppose it would drop as system and ambient temperature dropped, but think that most look at a quick drop over a few minutes as a sign of a leak somewhere. In case it helps, here’s a nice write up with photos on testing the ignition system... https://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/ignition-misfire-diagnostic-tests-3
  3. Still getting 60-66 psi at the fuel test connection? I’d agree that checking for spark would be in order now that it isn’t starting at all.
  4. Just a guess, but maybe you have a regulator or injector(s) slowly leaking the pressure down. Maybe leave the pressure gauge on overnight and see what it reads in the morning. You can also rig up a test kit to verify, use ball valves to isolate the supply and return lines at the fuel filter. The test procedure for that is in the factory manual, let me know if you need a link to it. Are any cylinders showing misfire counts in the scanner? When you start it and know it’s going to be difficult, does holding the ignition on for a few seconds help (allowing the pump more time to run before trying to crank)?
  5. Can you clarify - With ignition off, does it hold this pressure or drop off quickly? There is a section in the manual for fuel pressure testing which covers how to isolate the supply and return in diagnosing leaks at the injectors, regulator or pump. Are the injectors/regulator original? Does the ECT read a normal temp at cold start (around ambient) and stops at around 195 (or around your thermostat setpoint)? Usually, you’ll see a hard hot start when when these flake out, but holding the gas to the floor puts it in ‘clear flood’ mode and is a workaround. This stops injector flow.
  6. On the question about the catalytic converter/exhaust restriction, you can use a pressure gauge in place of the oxygen sensor to measure upstream pressure: Sent from my iPhone using Tapatalk
  7. I’d start with taking care of the codes. GM published diagnostic tables for each trouble code (DTC) that gave the technicians step-by-step procedures for remedying each code. These are available in the factory service manuals here... http://67-72chevytrucks.com/vboard/showthread.php?t=700011 ...or at online subscription based services such as alldatadiy.com. Since it’s a bit easier to navigate and is pretty close to the factory manual, I’d get a subscription (it’s around $30/year) and go through each code’s diagnostic procedure to see what the issue is. Good luck, I hope this helps. Sent from my iPhone using Tapatalk
  8. For the alternator, it’s probably the 105A with the internal fan, but here are the three ones from Rockauto for a visual comparison. Here are the GM part numbers for the timing chain, it looks like the difference is 1/2 vs 3/4 tons, so there’s only one to chose from (14087401). Maybe you can cross-reference with that. If the original u-bolts lasted this long, I’d be inclined to use the GM/Delco ones but maybe others would have recommendations. Sent from my iPhone using Tapatalk
  9. This is on a Corvette, but maybe it will help with navigating the menus. After the automated bleed, you would follow up with a manual bleed at all four corners to get any air expelled from the ABS unit. https://www.corvetteforum.com/forums/c5-tech/3795709-tech-2-bleed.html Sent from my iPhone using Tapatalk
  10. The dirty gray body sealant below is what can sometimes crack and let water in. See the screw in the black trim on the right? Remove that and pull up, apply caulk or maybe RTV to that screw hole and any others that you can get to. I didn’t have to remove the wiper arms when I did mine. Sent from my iPhone using Tapatalk
  11. The diagnostic charts for those codes all reference TRANS fuse #20 (10Amp). You can get a subscription to alldatadiy.com for around $30/year. It has the diagnostic tables for each of these codes, it may be worthwhile looking into. For example, here is P0740 for a 98. Sent from my iPhone using Tapatalk
  12. I’m not sure what years the 3/4 and 1-tons used the hydroboost, but would assume that it was for the majority of the model run. A scanner can be used to bleed the ABS module. It would be followed with a bleed at all four corners. A shop did mine two or three years ago for around $80. That may be a more effective way to purge the air. Sent from my iPhone using Tapatalk
  13. Best I can figure, for the half-tons at least, is this... C/K105 (16) two door Tahoe 107 (03) two door cab, short bed 107 (06) four door Tahoe 107 (53) extended cab short bed 109 (03) two door cab, long bed 109 (06) choices are a Suburban or four door utility. Since there is a 3/4 ton version (209) then the suffix 09 must be a Suburban or a long bed truck. Suffix 07 would then be the short bed version, the Tahoe. 109 (53) extended cab long bed Sent from my iPhone using Tapatalk
  14. Here are the model breakdowns for 1998, maybe it will help. The numbers in parentheses are defined at the end of the table. For example, (53) is a two door extended cab. So “K209 (53)” is a four wheel drive, 3/4-ton two door extended cab. Sent from my iPhone using Tapatalk
  15. This is the diagnostic for a 1998 with the 350. Not sure if that’s what you have, but would think that the Passlock function would be the same or pretty close to your 99. Hope it helps. It looks like a scan tool may be needed for most of this. Sent from my iPhone using Tapatalk
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