Chicken Drumstick Posted January 4 Share Posted January 4 We have a factory V8 90 pickup, it had the engine replaced with an EFI 3.9 a couple of years ago. I wasn't part of the swap and haven't really done much on the EFI's of this era. We are having an issue. Out in it the other day and pulling away the throttle stopped responding and the engine died. It now won't restart. It just cranks and makes no attempt to fire. It did this once in the summer, but an overnight park up and it fired back up. But not this time. Other symptoms that may or may not be related: -When cold the throttle is quite jerky at low speed. It gets better as it warms up, but not as smooth as it should be. -When hot/running temp the idle can sometimes run very high (no tacho, but est 1500-1800rpm). It does this after a bit of a run normally and when you pull up it'll idle high for a short while, before returning to normal. -Major battery drain which it didn't have on the carb 3.5 engine. So must be something from the EFI loom/ECU causing it. It'll drain the battery in a few days parked up. Looking at the ECU it seems to be a 14CUX, I understand these might be ODB 1 compatible. Are there any recommended diagnostic/scanner tools I should be considering? What should I be looking to bug track next to get it running again? If I crank the engine enough/pump the throttle I can smell fuel. So I assume it is getting petrol. I'm guessing either it isn't sparking or the injectors aren't firing. But I'm not really sure what or how to check further. Both of these relays click when the ignition is turned on. Quote Link to comment Share on other sites More sharing options...
Eightpot Posted January 5 Share Posted January 5 Sounds like there are a few issues running parralel there - long time since I worked on them but the ignition modules often played up which made them hard to start. There should be a road speed module fitted on the speedo cable which adjusts fueling at low speed to stop jerkyness at low rpm, sometimes not fitted on a conversion. Ecu wiring is fairly simple and should just take a live feed from an ignition wire to light it up - just wondering if it may have a permanent live which is keeping it on and draining battery? Probably not much help but got the ball rolling.. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 5 Share Posted January 5 The high and rough idle sounds like the MAF is disconnected or failed to me, only know this as forgot to plug it back in once Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 5 Share Posted January 5 13 hours ago, Chicken Drumstick said: If I crank the engine enough/pump the throttle I can smell fuel. So I assume it is getting petrol. I'm guessing either it isn't sparking or the injectors aren't firing. If you're getting fuel injected then the ECU is seeing a signal from the ignition telling it the engine is turning, and it's injecting fuel which means the ECU is alive & the injectors & fuel pump are working. I suspect the dying is the ignition side of things - ignition amp or coil or the like. The high idle could be a stuck/gummed-up idle air stepper (back of plenum) or a few other things, ISTR the 14CUX likes to see a speed signal from the gearbox and can get a bit funny without it. It's a very simple old hector and the problem will be something simple too. Quote Link to comment Share on other sites More sharing options...
Doorknob Posted January 5 Share Posted January 5 Whilst rebuilding mine, I also experienced problems with the ignition coil. I had 2 problems, 1. there is a wire running from the minus on the ignition coil to the ECU, this wire had a tiny tear which meant it did not like tell the ECU it was working (I think?) 2. The amplifier module in mine had died Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 5 Share Posted January 5 1 minute ago, Doorknob said: there is a wire running from the minus on the ignition coil to the ECU, this wire had a tiny tear which meant it did not like tell the ECU it was working (I think?) Very common, black/white wire IIRC. Quote Link to comment Share on other sites More sharing options...
AlWorms Posted January 6 Share Posted January 6 for the 14CUX, Get RoverGauge - buy or build a cable and the software is free. It's a lifesaver. Quote Link to comment Share on other sites More sharing options...
Junglie Posted January 8 Share Posted January 8 On 1/6/2024 at 5:35 AM, AlWorms said: for the 14CUX, Get RoverGauge - buy or build a cable and the software is free. It's a lifesaver. Don't suppose you have a link, do you? Quote Link to comment Share on other sites More sharing options...
AlWorms Posted January 8 Share Posted January 8 Rovergauge: https://github.com/colinbourassa/rovergauge Cable instructions are on the page (I added wires to the existing diag plug and fitted another type of connector, but you could also cut it and fit you own). You can buy cables too; https://www.ebay.co.uk/itm/315082558415 I have no affiliation or experience with that seller and they are probably available other places. That Ebay one is probably a good deal, as the connector is hard to find, but it's all set up, ready to go... and probably only costs double buying the basic parts and then having to muck around assembling anyway. Click on the green "CODE" button and select "download ZIP" from the menu: You need the Libcomm software linked on that page too, and the instructions are further down the page on setup etc. 1 Quote Link to comment Share on other sites More sharing options...
Junglie Posted January 9 Share Posted January 9 Outstanding, thank you @AlWorms 1 Quote Link to comment Share on other sites More sharing options...
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