View Full Version : '88 351 rough idle, gets worse when hot
09-24-2008, 09:47 PM
I've got an '88 351 that starts just fine, idles fairly smooth but fast (1200 rpm required to prevent stalling), and then stalls out below at all power settings below 1800 rpm once it warms up. Also, acceleration and top end speed has dropped way off...I can only get 30mph! I've replaced the spark plugs, fuel filter, carb-spacer gasket and spacer-manifold gasket. No real improvement. I'm thinking of testing the fuel pump pressure or maybe checking the fuel lines for blockage. Any suggestions? Thanks in advance!
Do a search here- htere have been a few others with very similar symptoms. One solution was to check/replace the advance springs in the distributor.
09-28-2008, 09:02 AM
Thanks for the advice, JimN! I ended up replacing the plug wires before getting into the distributor and that made the old girl idle much much better. Stayed around 900 rpm (still a bit fast) and didn't worsen when the engine warmed up. Then I decided to throw on a new cap and rotor. I took a look at the advance springs and they looked fine. Since the new cap and rotor, I can't even get ignition at all. Didn't mess up the firing order, checked that with the manual. Wondering if I shorted something out because I think I had the battery on (woops) when I put on the new cap/rotor. Looking at testing the coil next although I don't really know how to do that...any other ideas? Thanks in advance.
Don't crank it too long with no spark- it'll still draw gas into the cylinders and that will eventually collect in the exhaust, with some getting into the oil. That dilutes the oil and it loses its ability to lubricate.
Make sure the coil wire and plug wires are inserted fully. Borrow a timing light if you can. If a friend doesn't havae one, AutoZone and some other places loan tools.
Do you have a test light or multi-meter? You'll need to make sure the coil is getting voltage. If it's not, look at the gauges tomake sure they react when yo uturn the key ON.
Look at the rotor and make sure the center post is still there. I had one that came out and you'll never get spark with that.