Antonio Valencia, Robin van Persie and Wayne Rooney scored a 13-minute trio of goals in the first half to put the visitors in the driving seat at Craven Cottage.
Despite Alexander Kacaniklic reducing after the break, there was no way back for the hosts as they suffered a sixth defeat of the league campaign.
Jol, however, claims his positive mental attitude can help drive the club forward.
"I have no fear," he said. "In the past I always said 'no fear, Martin is here'.
"I don't fear. Sometimes I worry if the supporters are at my back, but on the other hand I think it's better they are on my back than on my players' backs.
"I know that there are always six or seven clubs in trouble and I said to somebody yesterday (Friday) - 'If you saw (Roberto) Martinez, he was always in the bottom three of the table, then after games he was always fantastic'.
"So that is where I get my belief from, because I know that we are a better team than at least six or seven other teams and we will pick up points. I think we will be fine in the end."
But Jol bemoaned his side's defensive collapse in the middle of the opening period, which allowed United to build a healthy lead.
"We looked awful over a short spell of time in the first half," he continued. "We started off well, then we gave it away and they played through our defence like a knife through butter.
"At half time, we sat together and they were so good, my boys. They wanted to do well and they wanted to show character and that is what we told them as well.
"I can't say that I'm a happy customer, but I was really satisfied that we came back and we could have scored a second.
"3-2 would have looked a bit better, but three goals in 12 minutes - you fear for the worst."
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