When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Feel kind of silly at this point as I've probably spent more on this car in the last 3 months then what it's worth but I've owned the car for 20 years so it was hard to consider selling it for another on.
Na, don't be, we take love and tender care of our Vettes !!
You mention something important about the oil pressure. Our cars wont start until they see a set PSI (or higher) of oil pressure. It's possible that may be part of your issue as well
Not So, as there is a circuit that engages the Fuel pump relay, a very short signal, see pin A1 to fuel pump relay. If your engine will notstart until the oil pressure is up, then there is an issue is the fuel pump relay circuit. Check for fried points in this relay or lack of signal from the ECM... Pesky but vital
And a photo of my little gal Lois, with the factory hardtop
Michael.....
You can also aptly battery voltage to pin G on the OBD service connector. See attached diagram.
Another little PEST at times is the hidden away forgotten Fuel pressure accumulator It is between the fuel filter and engine. Can be a pain if its partially plugged, the Ethanol fuel doesn't help, diagram also attached.
You mention something important about the oil pressure. Our cars wont start until they see a set PSI (or higher) of oil pressure. It's possible that may be part of your issue as well
Not So, as there is a circuit that engages the Fuel pump relay, a very short signal, see pin A1 to fuel pump relay. If your engine will notstart until the oil pressure is up, then there is an issue is the fuel pump relay circuit. Check for fried points in this relay or lack of signal from the ECM... Pesky but vital
Fuel pressure accumulator - I don't see this on my car or recall it in my shop manual, which is packed away for our move. Is this something added on the later cars? I've had fuel pressure issues for a while and even after replacing the pump and regulator it still wasn't holding pressure. I just changed the filter as part of my current projects but I'll scan for this as well. Thought my issue was a leaking injector so I cleaned those as well as part of my current project too.
I know, it can be annoying at times. Have you verified a low or Dipping Fuel Pressure while the engine is running ??
I don't have an issue with holding fuel pressure on my C4 Convert, it's the initial fuel pressure priming that's on the Blink someplace. Like I wrote, I'll probably just installed a push button switch in the drivers area and use that to engage that fuel prime relay,. I've never found this accumulator is my C4 nor on a few others, both the TPI and LT1 models as shown on the diagram. I've tested with a fuel pressure gauge on the fuel rail and that's fine, we even strapped the fuel pressure gauge o the windshield and propped up the hood so We could test drive, good. But the prime circuit is def the problem on my C4...It's been so long ago I don't quite remember how Steve (life long friend and also Engineer) made a fuel line Plug so We could disconnect the fuel pressure line at the engine pressure held .. When I inspected the relay Wiring, the Hot wire to the fuel pump was fried. Replacing the this relay and wiring pig tail was only short success. This worked for a few months and then became intermittent, that soon fell to a failure on this fuel pump prime circuit. Had enough,, manual prime switch at thus point in time !! I'm going to upgrade to a LS ECM and Vette wiring harness, going to the sequential injector firing and a much better ECM.
-- You might try capping off he pressure side on the fuel line and the engine, like we did, to determine if the pressure loss is before of after this point. I've seen fuel pressure issues even with new pumps, and electrical supply to EFI pumps too.
I recently helped a friend install a very low mile (32K) -95 Vette LT1 into his wife's '73 Euro Mercedes Convert. The engine price was $1000 with a new Hewell ECM and wiring harness. My friend had paid a Shop $$$ to do the job, but half way through they told him to come get his Merk. So we gutted their work and started over again, one of those Saturday only projects. It's a very low mile Covert, just mint condition and Its all black, so why not.
To the Point, There is only one issue, occasionally when stopping at a Traffic light or stop sign, the RPM drops and sometimes the engine dies.
I've been through the fuel system and Vacuum system,, at the build,,,new pressure reg, pump, and injectors, all new Vac lines,.. So I'm at the point Vacuum or Fuel ,,, which ?? For now We'e on hold until next Spring.... The plan is to drive this Frankenstein and start with a Vac Gauge inside so we can watch, and see if the Vacuum pressure drops when applying the brakes. I'm hopping this isn't a fuel problem !!
Good Luck, let me know if you have any ides or if you get yours figured out..
Asking the pro's here. The braided hose lines from TPIS were made to connect to the factory hard lines at the front of the engine. While looking at the car I noticed that their is a clear path to the hard line connections at the fuel filter. I was 100% planning on connecting to the hard lines at the front of the engine then I realized that they are only 80% hard lines and have rubber hose in the middle to allow for flexibility. That hose has got to be getting worn down as it's been on the car since new. What are the thoughts about removing that porting and just getting some longer fuel line and connecting the rails to the joints by the fuel filter? I noticed the return line is spliced their as well from the factory.
This worth while or am I overthinking things?
Also, dumb question but will ask to be 100% sure since the instructions don't state it. The feed line is where the Fuel pressure regulator and the other side is the return, right? It's obvious on the hard lines as they are different sizes but on the rail itself they are the same fittings so I wanted to be 100% I hooked it up right.
I should add. If tapping into the hard lines by the filter is best, anyone know the correct fittings already? If not, I'll start that research but rather not re-invent the wheel unless a need to.
Finally got out to the shop and made some progress on the car. At this point, plumbing the fuel system is about all that is left. I bought what I thought would work but the fuel pressure regulator side wont work so I'm having to find another solution.
Dang near everything is new under the hood now. I just hope it all works and my car finally stops leaking fluids now, too...
CAPT MIKE DEPENDING ON UR C4 YEAR THERE IS A NINTH INJECTOR ON DRIVER SIDE BETWEEN #5 & #7 INJECTOR. THIS NINTH INJECTOR IS CONTROLLED BY COLD START SWITCH LOCATED ABOVE THE H2O PUMP NEXT TO THE ECM TEMP SWITCH. IF U HAVE THE GM FACTORY SERVICE MANUAL, STUDY THIS CIRCUIT. ON NON-COLD START INJECTOR MODELS ECM/PCM CONTROLS EXTRA FUEL ON COLD STARTS.HOPE THIS HELP.
re the cold start injector, thanks. Yes I know about it, but even in the summer there's a cold start issue. I need to get her out of the cargo trailer next week and into the garage. First up I'm going to connect test LED's on both fuel pump relays,, "Coil" contacts, and then the 12 Volt DC Vbat outputs with jumper leads and hopefully there's a clear failure mode.
I'm in the downhill slide on my crazy '37 Chevy Coupe build. I'm firm on swapping out the ECM and engine wiring in my old lonely C4, I just need to decide which ECM and harness. I have a 2001 Vette ECM & OEM wiring w a LS1 T-56 in my '56 Chevy 210, a fairly easy install because the OEM engine harness is only an engine harness with no other devices included. This car performs marvelous for over 12 years now, trouble free.
My '37 Chevy I'm using a 2008 Vette ECM & OEM harness on the LS3 crate engine. This ECM is more desirable, but the OEM engine wiring harness incorporates other systems and it's a PITA to strip down the harness so just the ECM wiring remains. But I'll prob go with the 2007-2008 Vette harness and wiring plus I have all of the schematics and experience. . Both are true sequential wide band ECM's. Unlike the batch mode injector fuel control and old style narrow band Oxy sensors OBDI ECM.
I'm looking forward to getting this done and the del-a-lum front control arm bushings installed. !! Time to quit putting this off.
I got the one from TPIS. I like it but I only got it to help push the alternator away from my headers a bit to see if that hopefully let's it live longer. I'm super close now with my install. I got it running and drove it from my storage unit to my house. Off idle it would bog real bad but I'm told it's probably the tune from another thread I made. I sent my computer to TPIS this week for an updated tune so hopefully that gets me in the ballpark and I can start driving the car again.
12-24-2018, 05:01 PM
