Engine stalling when backing out of driveway.
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Junior Member
Joined: Feb 2021
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Engine stalling when backing out of driveway.
Hey there, been working on a pretty heavily neglected 87, 302/aod. So far I've changed plugs, wires, cap and rotor and harmonic balancer. Motor ran decent then. Just changed the IAC, MAP sensor, coil. Also bought a TPS and EEC, but I haven't put those in yet. I recently changed the motor and transmission mounts, and since then, the engine has idled rough and stalled. It only stalls right when the truck exits the driveway. The restart is somewhat rough, but it will go back up the drive no problem. The rpms do drop around 500 when put in gear, and if I switch between gears quickly, it will occasionally stall. Whoever had the truck before me hacked into the vacuum lines and wiring harness pretty good, so I've been slowly trying to piece that back together, but it's never stalled until now. I've checked fuel pressure and it runs around 32 at idle, the upper manifold gasket has been replaced, along with the throttle body gasket. I've gone around and sprayed starting fluid, but couldn't find any noticeable leaks. Sorry bout the book, but any help would be appreciated.
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
STOP CHANGING PARTS unless they're due on the maintenance schedule. Of all the parts you mentioned, the ONLY ones on the schedule are plugs.
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What test did each part fail, and did each replacement pass the same test? If the answer is "none", put the original IAC, MAP, & coil back in. I'd return that EEC for refund ASAP. Do not change the TPS unless the original fails this test:
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Is the end of the driveway a big bump or steep hill? What happens if you drive within 20' of it, but don't cross it, and just let the truck idle in gear? What happens if you restart, and continue down the road? What happens if you park the truck on the road overnight, and then drive it away from the house the next day? What is the fuel pressure just before it stalls?
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Be sure to include the number of gas tanks in your signature. If you unplug the fuel pump on the frame rail under the driver's seat, and cycle the key to RUN, can you hear the fuel pump in the selected tank running?
It will be easier to continue helping you if you put ALL the truck's details into your signature as this page explains:
(click this text)
(click this text)
What test did each part fail, and did each replacement pass the same test? If the answer is "none", put the original IAC, MAP, & coil back in. I'd return that EEC for refund ASAP. Do not change the TPS unless the original fails this test:
(click this text)
Is the end of the driveway a big bump or steep hill? What happens if you drive within 20' of it, but don't cross it, and just let the truck idle in gear? What happens if you restart, and continue down the road? What happens if you park the truck on the road overnight, and then drive it away from the house the next day? What is the fuel pressure just before it stalls?
(click this text)
Be sure to include the number of gas tanks in your signature. If you unplug the fuel pump on the frame rail under the driver's seat, and cycle the key to RUN, can you hear the fuel pump in the selected tank running?
It will be easier to continue helping you if you put ALL the truck's details into your signature as this page explains:
(click this text)