Hello guys! So I bought a 1994 ford Ranger 4.0 last August so I can save money and put this engine in my 1986 with the 2.9 because the 2.9 is UNFIXABLE despite replacing every single computer, sensor, ENTIRE fuel system etc.

I purchased this 4.0 because we have had them in our family out over 200k without problems. Now I am having the exact same problems that my 2.9 has.

Last month I started getting stranded got a brand new battery and high end non rebuilt alternator. Fixed various issues. I started noticing on starting my truck, I no longer heard the fuel pump come on when I would get stuck. So I bought a new fuel pump from autozone and new fuel filter installed it, problems went away. About 2 weeks later I swear I heard my fuel pump while driving in town... (I honestly dont know if fuel pumps are always on or on only when I start, i dont know squat) but I noticed the noise when I never ever hear it after starting. But no problems. Then I started driving and the engine would shut off, no power steering etc almost drove off road. got stuck... fuel pump wasn't coming on again. I did the turn key forward without starting the vehicle trick 3x to see if it would start and if so would indicate I need a new pressure regulator.. didn't work... so we replaced the fuel pump relay switch.. instantly the truck fired up check engine light went away and was fixed!

now its been fine 4 3 days... then today up my driveway (somewhat steep) it hesitated... as in you stop moving forward even though your engine is still running.. then power came back... on the way to my folks place it happened again. Just miles later my truck died thankfully right in front of my parents house but easily started again..

I notice this only happens so far under load at lower rpms, low speed. Any ideas? I am worried this will be like my last truck... map sensor.. o2 sensor,,,, entire new fuel system cats etc until there is nothing left to fix and keep chasing your tail. I've been out of work for a month and a half and almost died with complications of a galbladder so now I am honestly embarrassingly a bit extra freaked out about unreliable trucks and things like this because of the places I have to drive through don't have cell reception, and being less capable right now

So I have 2 trucks I don't trust with tons of money in both with no money for a better vehicle. Can you help me fix this issue so I can go back to work and relieve my poor wife? I believe in these 4.0s not the 2.9. I'm reading the forums and see so many different potential problems (like my last truck) but I figured if I write out the exact history perhaps this would help. THANK YOU for all your help over the past few years

KnightOwl

 

Just another symptom update. I tested it again and noticed my battery voltage meter went up then down while I had the loss of power jerking hesitation problem, perhaps this is useful information