Loss of power

[Rabid Sloth Racing]

I had seen posts about the issue with the length of pipe prior to the MAF and normally have the filter set as far away as it can go and still seal. For testing I ran it even farther as seen below.

I did notice last night that when is started running rough, the boost gauge went from -20 psi to 0 while it was sputtering. As soon as it ran smooth the pressure dropped back to -20. I replaced the vacuum lines before putting the engine in but double checked them all to make sure there was nothing loose. I checked the actuator and it wasn't moving. I pulled the hoses and checked that both sides held vacuum, which they did. So I picked up a new solenoid. It runs way better now, but not great. There is still some surging at idle but I'll wait till it's cooler to see how it drives at speed.

I did pull the fuel line up at the rail last night and it looked like plenty of volume but I haven't checked pressure yet. Once it cools down my test drive might be by Harbor Freight for a pressure gauge.

Although I checked for loose hoses I'm not 100% sure there's no vacuum leak so I'll cap the brake booster line and blow propane to check everything else.

So far: New O2 sensor but it likely needed one. New plugs but they were badly needed. New boost solenoid but it was completely busted.

 

[Desert Sasqwatch]

Just to cure my curiosity, rotate the MAF pipe about 90 degrees so the sensor is closer to the top of the fuse box, positioning it on the outside of 45 degree bend coming from the filter. See if this makes a difference, then rotate it 180 degrees so the MAF is furthest away from the fuse box, positioning it on the inside of the 45 degree bend.
There will be differences in the airflow at these positions from where it is now when the airflow velocity is slow. Maybe it will help, maybe it won't but can't hurt to try it.

 

[Rabid Sloth Racing]

Hey Sas, I tried it in nine orientation combinations with the bent pipes. Also tried it in three orientations without the second bend and just the filter connected to the MAF tube. I couldn't tell a difference. I even tried loosening the upper 90 and rotating it while the engine ran... Maybe once I get a smooth idle I will be able to tell something... but not yet.

 

[Desert Sasqwatch]

Ok, sounds like you were already thinking about my curiosity questions and a full step ahead already.

 

[ctuinstra]

There is still some surging at idle but I'll wait till it's cooler to see how it drives at speed.

Do you have upgrades, larger injectors, etc.?

We always fought the idle surging. Typically it's because it's too rich or too lean at idle and the ECM is fighting it. We had a lot of problems with it with the 60lbs injectors. But now that I have the boost reference fuel pressure system, it has to be way out of wack before there are any idle issues. In fact I was able to lower my idle speed back down to default and it idles really good.

 

[Rabid Sloth Racing]

While I was waiting for it to cool down I went ahead and cleaned the throttle body.

I then took it around the block... Very very slowly... since that is all it would do. Anything more than a light push on the pedal and it falls on its face. Unplugged the MAF and tried again but it didn't change anything. There's just no power.

I missed getting to the store in time for a fuel pressure guage so that's tomorrow me's problem now.

As for upgrades? Good question. I know it had the worlds cheapest aftermarket intake on it. I found the phone number for the previous owner but he didn't return my calls. But if it was upgraded injectors or similar would it go from running ok to not at all within a mile?

 

[ctuinstra]

As for upgrades? Good question. I know it had the worlds cheapest aftermarket intake on it. I found the phone number for the previous owner but he didn't return my calls. But if it was upgraded injectors or similar would it go from running ok to not at all within a mile?

No. Just curious if there are other things that may come into play here.

It could be so many things at this point. Fuel pressure gauge is a good start. As you probably already know, we ended replacing our twice, all AC DELCO.

 

[Rabid Sloth Racing]

Looks like I get to learn the fuel system on these things.

When I cut on the key to first position the pump cuts on for 4 or 5 seconds. It pressurizes up to 17 psi. Then the relay kicks off and the pressure drops back to 0 psi over about 5 seconds. This drop isn't due to a bad gauge or leaky connection, I pressurized everything manually with a Mityvac just to be sure.

When I start the engine the pressure rises and bounces between 15 and 20 psi and again rapidly drops to 0 when I kill then engine. I don't think I'll be breaking any dynos with those numbers.

I don't know the Ecotec system, but could this be like a stuck ball valve or something similar in the pump? Beat the pump with a rubber mallet and see what happens?

 

[Rabid Sloth Racing]

Update: I beat it with a rubber mallet. Now it only gets to 15 psi with the key in 1st position...

 

[ctuinstra]

Looks like I get to learn the fuel system on these things.

When I cut on the key to first position the pump cuts on for 4 or 5 seconds. It pressurizes up to 17 psi. Then the relay kicks off and the pressure drops back to 0 psi over about 5 seconds. This drop isn't due to a bad gauge or leaky connection, I pressurized everything manually with a Mityvac just to be sure.

When I start the engine the pressure rises and bounces between 15 and 20 psi and again rapidly drops to 0 when I kill then engine. I don't think I'll be breaking any dynos with those numbers.

I don't know the Ecotec system, but could this be like a stuck ball valve or something similar in the pump? Beat the pump with a rubber mallet and see what happens?

Bad pump for sure. You should have 58psi for a SC engine (42 for N/A). The shouldn't bleed off very quickly. The one-way is in the pump motor itself. Unless you have a leaking injector, that could leak some out and into the engine.

But 17psi is not hardly enough to start the engine, much less accelerate.

 

[ctuinstra]

Beat the pump with a rubber mallet and see what happens?

Replace it. There is no reason to keep messing with it if it doesn't pump up to the correct pressure. The last thing you want is the pump to start working and then give you false hopes its fine only to leave you stranded somewhere. RA has the OEM pumps (and cheap ones also).

 

[Rabid Sloth Racing]

I pulled the pump to take a look at it. When it went in the tank it was in one piece. It came out in four pieces... I'm not really sure how it was getting any pressure, since by the time it was out the actual pump wasn't attached to anything. Got the only pump in town (no name cheapy from ORiellys). Took it for what ended up being a two hour shakedown drive. It was scary on the donor tires before when it was running ok. Now with good plugs, O2, MAF, and fuel pump its terrifying. It'll go sideways at half throttle in third. Next budget item has to be wide and stickies.