omega_rugal Posted December 10, 2016 Share Posted December 10, 2016 as part of the LPG conversion to my MJ, i came across this situation: for some reason it won't`start directly on LPG (i`m pretty sure it`s the reducer`s fault) but if i start it on gasoline for a few seconds then switch to LPG, it starts... runs rough since i haven`t advanced the ignition but that`s normal... but if i don`t switch to LPG and just let the engine on with the fuel pump OFF... it keeps running, for like a minute or so as long as it idles it keeps running, it stalls if i try to rev it up... is it possible that the fuel system is "sucking" gasoline with the fuel pump off? i mean there`s the pressure regulator conected to the fuel line direclty (the small plastic thing that disconects them when it`s off was broken so i therw it away and joined the 2 lines)? too bad the renix 4.0 doesn`t lend itself to run on LPG, at least not easy as other less awesome engines... Link to comment Share on other sites More sharing options...
Hypoid Posted December 10, 2016 Share Posted December 10, 2016 I found the 4.0 can idle on 15 lbs of fuel pressure. Link to comment Share on other sites More sharing options...
gogmorgo Posted December 10, 2016 Share Posted December 10, 2016 Yup. I had the same. It'll idle but touch the throttle and she dies. It's likely just the residual pressure bleeding down. Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 11, 2016 Share Posted December 11, 2016 Get a primer solenoid. Mine had no issues starting on propane with one. Link to comment Share on other sites More sharing options...
omega_rugal Posted December 11, 2016 Author Share Posted December 11, 2016 Get a primer solenoid. Mine had no issues starting on propane with one. how did you fix the timing advance problem? Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 11, 2016 Share Posted December 11, 2016 I ran a HEI, so not quite the same. I think you might be able to mod the CPS enough to get a decent amount of timing out of it, but that's about it AFAIK. If a guy wanted it to be dual fuel they could probably mod the CPS by leaving the factory sensor where it is, then putting a second one on in as far of an advanced position as possible, then run it through a high quality DPDT switch with shielded wiring. But either way you should be able to dump enough gas to it with a primer to get it to start. Typically propane doesn't start terribly easy, or has a long cranking time, because the regulators are demand based and it takes a while for it 'sense' demand given that cranking RPM just isn't that high. Link to comment Share on other sites More sharing options...
omega_rugal Posted December 11, 2016 Author Share Posted December 11, 2016 i though about the CPS mod but is way too much trouble, the HEI distributor sounds like the only way to go... Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 12, 2016 Share Posted December 12, 2016 The HEI is much more simple. You don't need anything but one wire to run it. Link to comment Share on other sites More sharing options...
omega_rugal Posted December 19, 2016 Author Share Posted December 19, 2016 did you buy the HEI or made it yourself? i mean i have seen people talk about these here and there, what brand / model can fit a 4.0 renix? you mean this? http://67-72chevytrucks.com/vboard/attachment.php?s=c0c3197ad232fc5f383d42a790365b01&attachmentid=132119&stc=1&d=1112058692 because i`m pretty sure there`s an old I6 chevy pickup with a blown gasket i can rip apart, and a spare renix distribuitor with the right pinion, as i have read, is the only modification need (GM dis + AMC pinion) Link to comment Share on other sites More sharing options...
omega_rugal Posted January 3, 2017 Author Share Posted January 3, 2017 update: problem almost solved as i suspected, the reducer was not suppling enough vapours to start properly, too much dirt and greasy deposits were both clogging the lpg line, the lack of power under load improved enough to drive, no more stalls, i can say it`s running at 90%, now if i can do the CPS mod i could in theory reach a near 100% under most conditions which for me is a success for my first Renix to LPG conversion... and with gasoline prices going through the roof in 2017... oh and the truck doesn`t even have a gas tank now so forget what i originally posted... Link to comment Share on other sites More sharing options...
Eagle Posted January 3, 2017 Share Posted January 3, 2017 Yup. I had the same. It'll idle but touch the throttle and she dies. It's likely just the residual pressure bleeding down. ^^^ This. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 3, 2017 Share Posted January 3, 2017 I ran a GM I6 HEI with an AMC 360 drive gear on it. They will bolt in that way. Summit now sells one of their own brand for $140 or something, complete drop in setup and 100% new parts. I am on the fence about ordering one for my J-truck and ditching the Ford parts on it. Link to comment Share on other sites More sharing options...
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