87efi Posted May 27, 2023 Share Posted May 27, 2023 hello out there. My '87 RRC 3.5efi developed a cold start problem for about a month now and I can't figure out what the problem is. Hope someone her can help me out on this as I don't understand some things on the wiring. The engine got an overhaul about 1.5years ago-new Cam,pistons,bearings,injectors etc. The actual problem is that it nearly won't start from cold like the first start at the day. I've got to crank it about one minute or more till it "slowly begins to wake up". I don't know how to correctly explain it another way. Once running it revs and runs fine. Even when turned off and restarted. I checked all the sensors(tts cts) throttle potentiometer, pick up plate and so on-readings are fine (-i went through the Haynes book) ignition amplifier & coil are both new(amp: HELLA, coil NGK) the amp has been taken off the dizzy and is now living near the AFM. the wiring at the coil as follows: there's a white wire coming out the harness going to coil+ (coming from the ignition switch-that should be correct)?! Another one at coil+ goes to the condenser. Another one from coil+ to the ignition amplifier. From coil - I've got one wire to the ignition amplifier. From coil - another (blue/white) wire with a small black resistor (it's 'lucas' branded and has about 6.8kohms) to the grey Relay that's near the coil and below the AFM. Is that last mentioned wire correct? Respectively the mentioned whole wiring? Has someone experiences or a clue what could cause this cold start issues? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 27, 2023 Share Posted May 27, 2023 If it's flapper EFI then this is probably the wiring diagram: If it's hotwire (has lambda sensors): I'd suggest your ignition amplifier might be going bad, they like to fail with temperature so either won't work when they get hot or won't work when they're cold. Quote Link to comment Share on other sites More sharing options...
87efi Posted May 27, 2023 Author Share Posted May 27, 2023 (edited) Hello fridgefreezer Because of that known heat problem with the amplifier I mounted the new HELLA one on a separate aluminium plate including a heatsink near the AFM. Can you tell me from which wire the ecu (4cu & it's a non Cat vehicle) gets its signal from to pulse the injectors? As it can't be the ignition switched 12v on the coil+ ...it has to be the wire that has got the 6.8kohm resistor with two spade connectors which goes from coil - to the relay right beneath the AFM..is that correct? And can you even tell why there's a capacitor on coil+ ? I always thought such a thing is only needed when you run a breaker contact/dizzy..? But mine has got contactless ignition. I took a picture of the situation. Greets Alex Edited May 27, 2023 by 87efi Forgot to add picture Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 27, 2023 Share Posted May 27, 2023 As per the diagram above, White/Black from coil negative, pin 39 on ECU. Quote Link to comment Share on other sites More sharing options...
87efi Posted May 27, 2023 Author Share Posted May 27, 2023 Bowie69 There is no black/white wire at my coil. Only a white one which is ignition switch+(12v) The only black/white wire is at the socket of the grey Relay on the right of the coil (see the picture). That is the thing thats confusing me🤔 Quote Link to comment Share on other sites More sharing options...
smallfry Posted May 27, 2023 Share Posted May 27, 2023 Check the in tank fuel pump and filter. Might not be getting enough fuel pressure. Quote Link to comment Share on other sites More sharing options...
87efi Posted May 27, 2023 Author Share Posted May 27, 2023 Hey smallfry I did the 'move the flap by hand while ignition switched on'- test with both fuel hoses disconnected ending in a plastic bottle yesterday. Pump works as it should.(pump is working even while cranking by starter) But I have no gauge to measure the pressure actually Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted May 27, 2023 Share Posted May 27, 2023 Try jamming the butterfly open a bit to make pump run - see if it starts give it a good min to prine up could be a leaking pressure relief valve or low pressure from pump ? nige 1 Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 27, 2023 Share Posted May 27, 2023 5 hours ago, 87efi said: There is no black/white wire at my coil. Only a white one which is ignition switch+(12v) The only black/white wire is at the socket of the grey Relay on the right of the coil (see the picture). That is the thing thats confusing me🤔 In your picture the relay in the top right connects the white/blue from the coil -ve (with the resistor in it) to the ECU onto a white/black wire. The relay is a factory bodge to cut the fuel off on over-run by literally disconnecting the coil signal from the ECU, it's triggered by a vacuum switch mounted nearby when the engine is generating strong vacuum on over-run / deceleration. Quote Link to comment Share on other sites More sharing options...
87efi Posted May 28, 2023 Author Share Posted May 28, 2023 So the wiring itself shown in the picture is correct the way it is?! I didn't recognize the relay on any wiring diagram. So my fault.sorry. then I think I'll have to check that vac.switch...and the fuel pressure-thing.-? Thanks for your answers so far Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 28, 2023 Share Posted May 28, 2023 5 hours ago, 87efi said: So the wiring itself shown in the picture is correct the way it is?! Yes. The relay was not on every diagram. You can just jumper across the relay (white/blue -> white/black wires) with a small wire with two spade terminals crimped on to take that + the vac switch out of the equation. Fuel pressure is worth checking, it should come up to ~35PSI and stay there, the fuel pumps can go weak with age. If you've got an analogue tyre pressure gauge you can use that to check, just don't drown yourself in fuel or set yourself on fire Quote Link to comment Share on other sites More sharing options...
87efi Posted May 28, 2023 Author Share Posted May 28, 2023 Hey fridgefreezer Believe it or not- I had the same idea using my tyre pressure gauge as it's hanging around since I bought it and never was used. Only to be sure--i simply would have to put it in line to the fuel rail hose..? What I found out meanwhile: the plug at the CTS had one partially broken wire. I soldered a new plug to the loom..and it starts at it should. Not knowing if that's the whole problem as outside temperature is actually about 25degrees C. Thank you again for the support 2 Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 28, 2023 Share Posted May 28, 2023 3 hours ago, 87efi said: Only to be sure--i simply would have to put it in line to the fuel rail hose..? Yes... sort of... but reeeeeaaaly carefully! I'd be visiting the local hydraulics shop and getting them to sell you a little hose barb-to-tyre-valve adapter so you can screw it all together - you'd need to measure the pressure in the supply from the pump but with a short length of hose tee'd off to join it to the fuel rail so the regulator can still work, otherwise if you just put the gauge "dead" in the end of the supply pipe the fuel pump will go as high as it can manage which could be 100PSI of fuel pressure, which is not ideal and tells you very little about how well the system is working. Quote Link to comment Share on other sites More sharing options...
87efi Posted May 28, 2023 Author Share Posted May 28, 2023 I think I'll ask @ the local hydraulics will be the best and then give the thing a go. Thanks and a nice evening Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.