Hey all, first off had the day off so thought I'd haul the boat and do some fishing. Well coming home i'm cruising along at 120km/h (75mph) and my speed starts dropping off and no matter what I do I can't gain it back. Engine won't rev over 2000rpm.

It bogs like it's getting alot of air but no fuel. I noticed a noise coming from my fuel tank which makes me think its the fuel pump. But how did I get home after another 100km of driving at nearly half the speed limit with the 4-ways on? Noticed that sound, don't know if maybe its just on its last legs and it was just being nice to get me home.

I checked all vacuum lines, everything is connected to where it should be. My catalytic converter has been rattling lately which I know is one of my next jobs. Could that be the culprit being that i'm not sure but does it not create back pressure. It's rattling pretty good inside so I don't think there's much left of it.

Kinda choked about this after I just finished the all in famous aluminum plenum plate and gasket switch a few weeks ago. But again my truck is U/S. Good thing I have a 2-wheeler.

Any help or suggestions would be appreciated. Thanks. If this has been mentioned point me too the forum. I did a search but nothing came up along the same lines. Will be checking for vacuum leaks tomorrow and possibly looking through the haynes to see how tough the fuel pump is to replace.

BTW its a 98 RAM MAGNUM 318 5-SPD

 

OMG, how did I get so lucky as to beat zman to this one???!!!

Unscrew your pre-cat O2 sensor and see if it runs any better. The crumbled innards of your cat could indeed be creating back pressure.

If that doesn't change anything, I think the next most likely culprit would be your throttle position sensor; easy enough to test with an ohmmeter.

 

+1 on checking pre cat O2.
+1 more on beating zman to it!

Go to the DIY section and look for Factory Service Manual. Better than Haynes.

 

"+1 more on beating zman to it!"

LOL - probably the one night he's taken off all month, and here comes a big ol' hanging curveball that he would have knocked into the next county. That's OK, I needed something to cheer me up after what the Red Bums just did!

Sorry John, you snooze, you lose

***

To the OP: I'd just take the time you'd spend researching how to replace the fuel pump and just test the fuel pressure at one of the rails. 49 pounds would be great, but my 318 runs fine on about 43.

 

LOL.... yea I was snoozing at that time of the night.

btw, Texas is really good. LOL

 

(Rangers have a bad habit of a great winning streak - and then tanking for a game or two. Hope it was only one this time!)


crpunt - let us kow what you find out.

 

Thanks for the quick replies. I will take a look at the pre cat sensor first thing this afternoon. I know its possibly fouled from the plenum leak but do I need to just replace that sensor if the truck runs better after I unscrew it. I have no check engine light on from yesterday saying otherwise.

Have decided to order the y-pipe and cat. Figure its best to get it done now before the fridgid temps come around.

Don't know if this changes anything but I just remembered I noticed after I shut the truck off it would run fine for 5 mins and then die off again.

 

Your truck runs fine for 5 minutes after you shut it off? I see a problem right there.

Joking aside, replace the plenum first or at the same time you do the exhaust, or you'll ruin the new cat in short order.

 

"I know its possibly fouled from the plenum leak but do I need to just replace that sensor if the truck runs better after I unscrew it".

Just want to make sure you're clear on what I understand to be the point of removing the pre-cat sensor as a diagnostic measure. If your cat is truly plugged, taking out the O2 sensor will relieve some of the backpressure and the truck will be able to rev better. If that's the case, you don't just replace the O2 sensor, you replace the cat first. (I'd say "or hollow it out", but I'm one of those goddam hippie tree-huggers who actually thinks there's a possiblity that man's activities are negatively affecting the climate).

(Steps away after lighting fuse and waits for the fireworks to go off).

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" ...replace the plenum first or at the same time you do the exhaust ..."

Just to avoid any confusion, OP already fixed the plenum and is just dealing with some of the remaining consequences.

 

You live in Alberta, No smog testing there, and as you have done the plenum, ditch the cat for a piece of pipe and change the pre 02. Fuel pressure at the rail for a 96 up is 49psi. Do a dry/wet comp test as well or better yet a leak down test.