: Anyone with rough starts, loss of power..read this.

03-19-06, 08:12 AM
I have been chasing a very frustrating prolem for a long time. After the car sat for a few days without starting, it would take 5 to 10 attempts at it before it would crank over. Idle was rough, but only sometimes. And the odd time it felt like it was missfiring slightly. Also seemed to run a little hot after WOTing it. I was used to seeing temps around 94°C(driving) to 103°C(idle) but it was running about 3 degrees hotter than usual, even hit 108°C a few times. For the life of me I couldnt figure out what it was. No codes, new plugs, wires etc...

Finally a few weeks ago, the oil light started flickering during idle. Then the car would occasionally stall (also only during idle) The power loss became more evident at that point.... I brought it to the stealer, ends up my fuel pump was toast...the flashing oil light was indicating low fuel pressure. It was a rather costly fix. (fuel pump 650$CDN, plus labour) But now the car feels like its old self again. I didnt realise how much power it had lost because it was so gradual. When I got the car out and did some WOTs, my face strangely lifted and exposed teeth :D ..it was a strange sensation, seeing how I just left the dealer and spend lots of money...anyway, maybe this will help some people track down their own gremlins...this problem caused me lots of headaches and I could not find it untill it was really bad (neither did the dealer)

03-19-06, 10:24 AM
Man you probably could have gotten parts cheaper from the US and installed the pump yourself. if i recall its pretty easy on the STS, maybe a couple hours.. Canadian parts are way overpriced as im sure you are well aware of!

Regardless, lack of fuel rpessure will CERTAINLY do that to the engine.. Did you notice any noise from the rear of the car? Generally when fuel pumps get weak they start making noise.

03-19-06, 11:01 AM
How many miles when that happened on the STS? My car is at 93k and its making noises ocassionaly sounding from the gas tank.

Wouldnt a high flow fuel pump (warlboro etc) help you better though? Or would they be a total waste for a near stock car?

03-19-06, 11:12 AM
A high flow fuel pump wont do you any good because fuel pressure is maintained by the fuel pressure regulator! The pump doesnt know pressure, it knows VOLUME... Litres per hour, gallons per hour, etc..... if you increase the volume of fuel to the engine, it will obviously increase pressure.. however, the pressure is maintained by the FPR, and it simply means that more fuel will be returned to the tank...

That being said, the stock fuel pump can flow PLENTY of fuel! however, a warlboro would work nicely, especially if it was bolt on (i dont know if the caddy fuel pumps are similar to that of other gm's, maybe 3800 SC) as it might be cheaper than stock. but its not going to give more power...

If you want to see how the fuel pump is, simply check fuel pressure and if its in within spec (at WOT and idle) then its likely ok... I noticed GM fuel pumps are a little louder than in other cars, doesnt really matter too much, just an observation.

03-19-06, 11:48 AM
It has about 80K on it. And there was no noise or anything to give it away. Dealer told me the fuel pump was in the gas tank? Didn't really look and its way to cold up here to do something like that on my own without a garage, at the moment. I needed it done right away, hard to work withough a car. They gave me a CTS to boot around in while they had it in the shop and waited for the parts to be shipped.

03-20-06, 05:20 AM
Just went through the same thing myself. Car started and ran fine for about 10 mins one day and just quit. I could hear the pump when I turned the ign on, but it did sound a little louder than normal. Poured some gas into the TB and put a fuel pressure gage on it....got up to a whole 10 psi. I changed it out in the driveway, took a couple hours, most of the time was spent draining the tank (thats another story). Once the new pump was in, I took the car out for a test drive. I couldn't believe how much power the car had been lacking and all of a sudden was restored. The best part was my MPG has gone up by 4.5. BTW, I got an aftermarket pump at AutoZone for $240 (US) vs. the $460 the dealer wanted just for the pump.

03-21-06, 05:52 AM
I was having simlilar problems just before I wrecked the ETC. When it's back together if it's still doing it the fuel pressure is going to be the first thing I check.