this is a duplicate from the van forum, but there isn't much action over there.

I replaced my 1994 E250 4.9L-6 with one from a 1991 F150. The F150 had air injection in the head, my 1994 did not. I kept the 1991 setup because it was easier.

I thought when putting it in that the air injection system from the 1991 might have problems, as it would cause the O2 sensor to read different values for mixture than what was actually combusting, but I wasn't sure how to remove / plug the air injection tube as the fittings into the head are very rusty. To remove the air injection I'd have to cut the tube off and then use a socket, at which point i'm committed to removing the system.

long story short, my van idles ok (not great) and runs down the road ok for a little, but it will only take a load for a few minutes before losing all power. It think it's the air injection but i'm still not sure. I double checked all vaccum lines and they seem ok.

I did a forum search and found out that ford makes plugs for the head, but i can't find this part online, or a size bolt for the 4.9L (300) so I can get the plugs ahead of time

any suggestions on this?

 

I had to plug a head on mine, after replacing the heads with 1 that was setup for air and one that was not. Grrr... I just used a bolt, it was 5/16" coarse thread. I got the bolt, threaded it in until it was snug, marked it, pulled it out, ground into my mark with a dremmel tool (I know this sounds redneck!), and torqued it back in until the bolt head broke off. That port leads into the exhaust, so if you don't plug it you get a wicked exhaust leak, like i had! My bolt trick worked well at plugging that leak, but I will never get that plug out again...
BTW, since doing this my truck has run just fine. The air pump is a bit loud, but performance-wise that truck is solid.

 

thanks Bruce.


do you (or anyone else) know if the air pump would give the rough running problems I"m having, because if not I should start looking elsewhere.

 

It shouldn't. All it does is pump air into the cats to help them light off. You might try swapping the heads if you still have the motor from the '94.

 

thanks, maybe i screwed up the vacuum lines that control it. from what I gather it should pump when cold and then shut off when the cats are hot correct? In that case, it wouldn't be the cause of my problem...unless I had hooked it up wrong and it was running more often than intended. That's an easy check.

Next time I get out there to work on it I'll pull the pump hose off and see how it drives, and go through the vacuum lines again too.

 

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